All about Windows XP Activation

The short story

To reduce software piracy, Microsoft requires that you validate your installation of XP through something called Windows Product Activation (WPA), either by connecting to their servers through the Net, or by calling a number where you'll get to either talk to a human being (great job...), or some automated answering device.

In either case, you'll have to provide both the Product ID (which is derived from the 25-character unique Product Key that you used to install XP), and a hashed number based on different devices in your computer. This lets Microsoft tell if you used a well-know, leaked Product Key, or if you gave a friend your legit Product Key so he can also install XP on his computer (in this case, the hardware ID will be different, and he'll have some explaining to do when he calls MS: One license = one computer).

If things go well, you will be given a release code to activate XP.

Note that 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. If you make significant hardware changes or reinstall XP altogether, you'll get a new hardware ID, which will prompt a new activation.

Note that $SYSTEM32\WPA.DBL and WPA.BAK should be saved and restored to avoid reactivation only when performing a 'Repair' reinstallation of XP; Those files are useless when performing a full reinstall.

Updating the Product Key on an installed XP

If you used a leaked serial number ("Product Key") when installing XP, and you suddenly no longer can log on, looping through the activation part, here's how to change the Product Key on an installed XP:



I need to change my XP Product Key

There are different ways:

Can I install SP1 on a pirated XP?

You'll need to change the Product Key to something legitimate only only for the corporate editions of Windows XP Professional using a compromised or illegitimate key. Windows XP Home Edition and retail versions of XP Professional are not affected by Service Pack 1.

How to tell if XP is activated?

Go to Start>Run and enter the following:  oobe/msoobe /a

What is Slipstreaming?

Combining a service pack into Windows.

What to do if XP won't let me log on?

If you installed XP with a leaked key, here's what to do to get going:

  1. Buy a legitimate CD of XP
  2. If you can get into Safe Mode, proceed with an In-place Upgrade
  3. If you can't even boot into Safe Mode, boot with the legit CD, and proceed with a Repair Install. Normally, it won't wipe out your data, but stuff happens, so you may want to back them up before by booting from eg. Bart's PE or Knoppix.

Both proceedures are explained by Michael Stevens.