Ditto to what DaveW said. There are supposedly a million and one reasons for the infinite loop problem. Alot of people who have gotten this problem have something in their system that's set too aggressively - either memory timings or an overclocked video card or cpu.
No guarantees here but getting a quality 400W PSU is good advice for anyone in this hobby. Newegg has some excellent Antecs for great prices. And possibly the problem might be caused by insufficient or fluctuating voltage to your AGP slot.
Alot of the today's default bios settings are still "legacy". Disable every bios option that says cache or caching except for, of course, the L1 and L2 caches.
I remember one "electrical" guy said he solved the infinite loop by removing the screw near his video card that held the center of his mobo in place - go figure!
What sucks is that if you put your video card in another mobo or put a different video card in your mobo, you might never experience the problem.