Chances are you need to fully format the drive before installing XP again. You will need to use maxblaster or whatever program came with your hard drive to boot from and then do a full format and partition, otherwise the MBR is still intact and windows may still see an older version was once installed and give you headaches. be sure to install the latest IAAR right after you install XP, otherwise you will have to follow Clintfan's guide on installing it after the fact (which is a real pain)