The problem:
You have an already activated Windows XP installation on your computer and you want to format your drive and reinstall Windows XP, but you don't have the serial number of your Windows XP install disk or you don't want to waste time to reactivate Windows after the format.
With this procedure, you can easily backup and restore the Windows activation
(As long as you didn't make any hardware changes on your machine)
Solution:
The first step is, to backup your activation files:
1. Open Windows explorer and navigate to C:\Windows\System32
2. Copy the files Wpa.dbl and Wpa.bak to another media such a flash disk or another hard drive, like an external one.
Now you can reformat your drive and reinstall Windows XP.
When the windows xp installation finishes, windows asks you to activate your product. At this point say "No" and choose to activate later.
Then proceed to the next step, to restore your activation files:
1. Restart your system, and as your system boots up press F8 to access boot options (Windows Advanced Options)
2. From the menu options select to start Windows in safe mode (minimal)
3. After Windows loads in safe mode, open Windows explorer and navigate back to C:\Windows\System32
4. If you find the files Wpa.dbl and Wpa.bak in this folder, rename the files to something like WpaOLD.dbl and WpsOLD.bak
5. From the media where you copied the activation files earlier, copy your original Wpa.dbl and Wpa.bak back to C:\Windows\System32
6. Restart Windows
After Windows restart, your Windows will be already activated and now you can proceed with the rest of installation, like drivers or programs installation.
