computer science

Normally, when you reinstall Windows XP you need to also reactivate the operating system by phone or Internet in order to use it. This can be avoided by simply copying a single file from your old installation to your new one.

The 'wpa.dbl' file, located in the 'c:\windows\system32\' folder, indicated to the operating system whether the current hardware configuration has been activated or not. As long as you have not changed any of the hardware in your PC during the reinstall, you can simply copy the file onto a floppy, CD or USB key and copy it back into Windows after the reinstall to avoid the re-activation procedure.