Sp2 trashed my previous computer's XP build when I loaded it. It wouldn't boot anymore. It would go into a "boot loop". There was no repairing it. I had to FORMAT: C . I rebuilt the XP load INCLUDING Sp2, and then had to reload everything else. Took a whole weekend, and lots of swearing. That was 14 months ago, and that computer has had NO problems since. (My daughter has it.) I found out later that it was the presence of an old SCSI driver in my build that caused the SP2 install to trash my build.