I recently tried formatting and reinstalling Windows XP on my second laptop (Alienware Area 51m) with a normal Windows XP Professional SP 2 CD. It formatted just fine, and went through the first process just great. After rebooting it, and going to the installing windows part, it does not get any farther. It gives me a fatal error, stating "The signature for Windows XP Professional Setup is invalid. The error code is 800b0100. No signature was present in the subject."
If it helps, it had Windows XP Home and I'm trying to put Professional on it. I do not have a floppy disk drive in this so I cannot boot to a different OS. Also, it absolutely REFUSES to boot to CD-ROM or I could probably fix this problem.