If you have successfully activated the OS already, and if you are reinstalling it on the existing hardware, this trick should do just fine. Here it is: Copy the file c:\windows\system32\wpa.dbl to a floppy. Reinstall Windows XP. Boot to a DOS disk if you are using FAT, or to the Recovery Console if using NTFS. Copy the file from the first step above back to c:\windows\system32. That’s it - because all of your hardware is the same as before, your copy of WinXP is still valid according to the previous activation. That’s it. That should do it!