you can avoid re-activation of Windows XP if you need reinstall of the operating system...
when you run for the first time the activation process the data on the activation success are saved in the file:
"%WINDIR%\System32\wpa.dbl", just make a backup copy of the file on a floppy disk.
After you reinstall Windows XP, on the same computer without changing the hardware configuration, at the first operating system boot just copy the files from the floppy to the folder: "%WINDIR%\System32".
