You can get to the recovery console (Assuming you can't get to safe mode with command prompt first) by booting off the WinXP CD (like you're going to install), but when you go to 'install' XP on the drive, it'll ask if you want to repair it. That's what you want. You'll need to know the admin password if there was one put in, and if you don't, AT's links with the tools would be very helpful.