Windows Product Activation (WPA)
on Windows XP

Version 3.1 — Last Updated April 11, 2005
by Alex Nichol, MS-MVP
© 2001-2005 by Author, All Rights Reserved

One new feature in Windows XP that has caused great concern is Windows Product Activation (WPA). There are a great many rumors, and much misinformation, from which you might be led to think that WPA is going to call Microsoft every day and say just what you are doing with your computer; that, if you make any changes at all to your computer hardware, the machine will be instantly disabled; and that WPA is a sneaky way for Microsoft to store personal information about you or your computer, or to begin charging you a monthly fee for your continued use of Windows XP. In fact, all of these rumors are false. WPA is a fairly easy-going check when Windows boots, confirming that it is still installed on the same computer as last time it checked. That’s all. But the rampant misinformation is understandable, because it is hard for the general consumer to find a simple yet comprehensive explanation of just what WPA is. This page tries to fill that gap by explaining WPA in a straightforward, detailed way — and to show that it will be a lot less trouble to most people than many have feared.

What’s the idea of WPA?

The Microsoft License for use of Windows has always been limited to allowing installation on only a single machine (and that excludes having the same copy installed on a laptop as well as a desktop machine: only MS Office is licensed for the combination). Microsoft believes that this has been subject to much casual abuse. WPA is a means of ensuring that a single copy is not installed on more than a single machine.

So, within the first 30 days after installing Windows XP, you must get the system ‘activated’ if you are to be able to go on using it. This involves the computer dialing in and giving some information about the hardware on which Windows is installed, receiving in return a release code which will be recorded on the system. More is said below about OEM copies provided preinstalled on a new computer

At subsequent boots, Windows checks to see that it is still running on hardware that it can recognise as being the same. If it does not match well enough, you will be unable to do more than backup files until you call Microsoft to explain — for example, that the old machine broke down and had to be rebuilt — and get a new release code.

What hardware gets checked?

The WPA system checks ten categories of hardware:

  1. Display Adapter
  2. SCSI Adapter
  3. IDE Adapter (effectively the motherboard)
  4. Network Adapter (NIC) and its MAC Address
  5. RAM Amount Range (i.e., 0-64mb, 64-128mb, etc.)
  6. Processor Type
  7. Processor Serial Number
  8. Hard Drive Device
  9. Hard Drive Volume Serial Number (VSN)
  10. CD-ROM / CD-RW / DVD-ROM

It then calculates and records a number based on the first device of each type that was found during setup, and stores this number on your hard drive. Initially, this is sent to Microsoft in an automatic dial-up, together with the Product ID number derived from the 25-character unique Product Key used in setting up Windows.

If Service Pack 1 has been installed, the entire Product Key is also transmitted: This can then be checked against a list of known pirated keys

The hardware is checked each time Windows boots, to ensure that it is still on the same machine. Also, if you subsequently perform a complete format and reinstall of Windows, Microsoft’s activation center will have to be contacted again because the information held on the machine itself (the number previously written to your hard drive) will have been wiped out by reformatting the hard drive. If your hardware is substantially the same, this will be done by an automated call without your needing to talk to anyone.

What does ‘substantially the same’ mean? WPA asks for ‘votes’ from each of these ten categories: ‘Is the same device still around, or has there never been one?’ Seven Yes votes means all is well — and a NIC, present originally and not changed, counts for three yes votes! Minor cards, like sound cards, don’t come into the mix at all. If you keep the motherboard, with the same amount of RAM and processor, and an always present cheap NIC (available for $10 or less), you can change everything else as much as you like.

If you change the device in any category, you have lost that Yes vote — but will not lose it any more thereafter if you make changes in that category again. So, for example, you can install a new video display card every month for as long as you like.

Note that it appears that if you boot with a device disabled (disabled — not removed), the device is not found in the enumeration — so if, say, you disable a network connection which uses the NIC and then reboot, you may be missing its three votes and find that a new activation is needed. If you are doing such things, take the Hint 3 in What about formatting a hard disk? below, and restore the files concerned once the NIC is back in service.

What if I make too many changes?

If, on Windows startup, there are not the required seven Yes votes, the system will, in the original version of Windows XP, only boot to Safe Mode. You will be required to reactivate by a phone call to Microsoft. You will have to write down a 50-digit number, call into the activation center on a toll-free number that will be given to you, read and check back the number you recorded — and explain the circumstances. In exchange, you will be given a 42-digit number to type in. This will reactivate your copy of Windows.

This is made easier if Windows XP Service Pack 1 has been installed: The system will continue to boot normally for three days, during which time you will be able to contact the activation center via the net. If the extra changes have been removed, or if 120 days have passed since the original activation, you will be able to use the automatic process once more

What about formatting a hard disk?

Two things are recorded for disks: the number of the disk drive itself, and the Volume Serial Number (VSN) of the partition on it.

HINT No. 1: The VSN is part of the data in the partition’s first sector, so it is changed when you reformat the drive. It is worth getting the freeware utility Volume ID to restore the original VSN. Before you reformat, run VOL from a Command Prompt, note the VSN (e.g., 1F2E-3C4B) in the second line. Then, after the reformat and new Windows XP installation, defer the new activation until you have run Volume ID to restore the old VSN, and rebooted. This is not essential — but it saves one of the ‘Yes votes’ against any future hardware change. (If you don’t wish to run this utility, the next best way to obtain the same result would be to delete the old Win XP files from the hard drive before reinstalling, rather than actually reformatting.)

HINT No. 2: Another thing that changes the VSN is converting a FAT 32 partition to NTFS. So, if you upgrade a system using FAT 32 to Windows XP and intend to convert to NTFS, do the conversion before activating the system. Remember, you can wait a while: you have 30 days before you need to activate. The machine’s hardware at the time of the first activation is what counts. Or, if you have already activated, use Volume ID as described in Hint No. 1. If you are doing this after activation, also first back up the WPA.DBL and WPA.BAK files, as described in Hint No. 3 below, and, after completion of the conversion, restore these files and reboot again.

HINT No. 3: It is valuable to back up the two files WPA.DBL and WPA.BAK from the Windows\System32 folder.Then, should they get damaged, or should you do a ‘Repair’ reinstallation of Win XP, these files can be copied back to restore the prior activation status. However, this only works in those limited circumstances. The contents of these two files is matched to the specific Windows setup; therefore, contrary to what many journalists and members of the user community have written in recent months, restoring these files will not restore your activation status following a reformat and clean install.

The disk drive and partition recorded will be the ones that the system has found first when doing the initial activation: normally the one from which the system booted. So, if you change that disk and reinstall Windows to a new partition, you have lost two of the Yes votes. If, though, you add a new hard disk, copy the original partition onto it with an imaging program, and retain the original hard drive as a secondary data disk, it will still be found by a later check. This is because it searches for all disks, and the vote will be Yes in both categories if it finds the original one, with the partition not reformatted.

What about a swappable hard drive bay?

Provided the swappable hard drive bay is for secondary disks (used for data), and the boot disk with Windows is still present, the swappable disks do not enter into the WPA calculation.

Changing the motherboard

Installing a replacement motherboard will change the IDE controller, and usually will mean that you change to a new, faster, processor. If the processor is one with a serial number (Pentium III), then you lose a third vote — including when you change to a processor with no serial number, such as an Athlon. If you also add RAM, or if the motherboard is one with an on-board SCSI adapter, that makes four or five categories now voting No — you would need an unchanged NIC to avoid having to call in for reactivation. If the new motherboard also has inbuilt video (and possibly even a NIC of its own!), you run right out of Yes votes with this one hardware change.

Again, this doesn’t stop you from making such a hardware change, nor from using Windows XP thereafter. The phone-in reactivation option was created for just this type of situation. Also, this is an extreme example. Due to the onboard features of some motherboards, this one hardware change is equivalent to several changes at once.

Re-activation on a new setup after adding devices

If you add devices, as mentioned earlier in relation to hard disks, the check at boot up will still find the original device, even if it is now in a subsidiary postion (e.g., as a slave hard disk). But if you format and do a new setup, it will be the device that is now in ‘first place’ that goes into the hardware hash sent to Microsoft. This means that this hardware category no longer will match — and will be seen as voting ‘no.’ This means that you may find the automatic activation rejected, even though you have not recently made any changes. Therefore, from the point of view of WPA, it is best to make such hardware additions subsidiary ones. For example, if you add another CD drive, have it as the secondary slave, and, if need be, move the original one onto the primary channel.

There is a useful program XPInfo which will give you a simple picture of which categories are currently casting Yes votes at the boot-up check.

How long does this go on?

The license for a retail version of Windows XP is in perpetuity. You get to use Windows XP forever, if you choose.

But Microsoft recognises that machines do get upgraded. If, following the activation after setup, you do not need to contact the activation center for 120 days (any changes you make during this time being seen as acceptable when the system boots), then the sheet is swept clean and you can start again using the current hardware as the new baseline to make more changes.

If you get a new computer, you are entitled to remove Windows XP from the one that is being junked, and install the same Windows XP on the new machine — but you will have to do the reactivation by a voice call and explain (unless, as was just mentioned, 120 days have passed since the activation was last performed).

Microsoft has said that if it ever becomes not worthwhile for them to keep this activation system going, they will take steps to allow users to disable it.

OEM versions

Restrictions of specific license types may limit the foregoing. OEM versions of Windows XP are licensed together with the hardware with which they are purchased, as an entity, and such a copy may not be moved to a different computer. Also, other specific license types (e.g., Academic licenses) are handled in different ways. These aren’t a WPA issue per se, but rather an issue of the license for that purchase, and therefore outside the scope of this discussion of WPA.

There are two versions of OEM Windows XP systems. One can be purchased separately, with qualifying subsidiary hardware, and installed with that hardware to an existing machine, to which it becomes bound. The software may be reinstalled and reactivated indefinitely as with a retail system as long as it is still on the original machine. It may not be transferred to a different computer. It is activated as described above, but if it were installed to hardware seen as not substantially the same, the activation would be refused as falling outside the license.

In the other OEM form, the system is provided pre-installed by a major supplier. Instead of activation, the system is ‘locked’ to the BIOS on the motherboard. The validity of this lock is checked at boot. As long as this is satisfied, other hardware may be changed freely, but any replacement motherboard must be for a compatible one supplied by the original maker.

If a BIOS-locked system is installed to a board where the lock fails, it enters a normal Activation process at startup. However, beginning 1 March 2005, the Product Key supplied on a label by the computer manufacturer, and used for the initial intallation, will not be accepted for activation. A new copy of Windows XP, with a license allowing installation on a different machine, will be needed. This means that any replacement motherboard (or upgrade to its BIOS) must be supplied by the original maker, who will ensure the lock is maintained.

Installation of Service Packs 1 & 2

Windows XP Service Pack 1 (“SP1”) introduces some further obstacles to systems that appear to have been pirated: It will not install at all on systems which appear to have used one of two well established “pirate” Product Keys, and a wider range of pirated and cracked keys will result in no access being allowed to Windows Update. These limitations are taken further with Service Pack 2

Installation of SP1 also will detect and fix a number of “cracks” used by pirates to circumvent the need to activate. Such systems will then need to be activated after SP1 is installed. However, regular, legitimate, installations of Windows XP will not need to be reactivated after simply becaues of installing SP1.

For more detailed discussion of the changes and their implications, see Microsoft’s article Service Pack 1 Changes to Product Activation.

Some things WPA does not do