Ok so here's my situation and what I'm trying to do...

I got a new video card and needs a AGP slot. My current motherboard never had an AGP slot so I got a new motherboard that had one. After switching motherboards I connected everything back into place and tried to boot up again and before it got to windows it reboot itself. Everytime it gets to the same spot and reboots. I havent even up in my new video card in yet either. I've herd that I need a new power supply, I've herd that I need to reformat, and I've herd that I need to repair windows. To be completly honest I'm new to the whole upgrading your pc thing. Any help would be appreciated.

Changing the motherboard requires reinstalling XP.

You can try a Repair Install but a Clean Install is preferable.

Guides to both options can be seen at this site:

http://www.michaelstevenstech.com/