Originally posted by: FlyingPenguin
Run the Dell or drive manufacturer's HDD diagnostic to make sure the drive is okay.
If the drive is good then you probably just corrupted the boot sectors. A boot sector repair should fix it:
Boot from the XP Install CD-Rom and choose the "Repair from Recovery Console" option during setup. At the command prompt type FIXBOOT and press the Enter key.
If this doesn't help then you'll have to perform a Windows XP Repair Install. Instructions here:
http://www.michaelstevenstech.com/XPrepairinstall.htm
Hope this helps...