Quote from a Gamespot forum:
Has anyone tried this? Looks interesting and will save a lot of hassle to physically reformat the HDD.
First Defense-ISR will "format" your pc in 2-5 minutes, and you can also choose folders to be excluded (save your savegames from certain death). Then it'll reboot your PC and it will be in the state when you made the backup (a fresh XP install without the crappy applications installed). No need to call M$ ever again to activate your copy of XP! There IS a god!!