if you use the factory restore discs and backups you'll be fine. The factory discs will restore your computer to a "new" state. Just make sure you're backups are updated and complete before you do this.
might i add umm its windows vista not xp, and also i tryed doing the recovery discs because i somehow eraced the second partiton and im going to do another backup. so the recovery dvd's will work after i format the hd?