Help, boot problem

Hi, I OCing my computer and I guess I set something a little to high that it didnt like. Well when it went to boot everything locked up. Whatever it did it even reset the BIOS on the motherboard when it happened. Now, my computer wont boot into windows without having the XP Cd in the drive. Otherwise it gives me a boot error message. Please help, if anyone has any ideas on what I can do to fix it without maybe having to reinstall windows, or even any ideas as to what caused it and what happened.