Stuart:
Did you make a recovery disc when you first booted the machine? If so, boot from that. If not, you’ll need to go the whole hog and delete all the partitions – assuming you have an XP Pro CD “nlite’d” as described in my post. You’ll need a boot disc to delete the partitions – try a Linux Live CD or something like BartPE: http://www.nu2.nu/pebuilder/