Replaced the motherboard last night. Then spent three hours trying to figure out why it is still resetting. The memtest came back clean, and it's almost [now] all new parts. Hooked it into another computers peripherals and power and it still reboot horribly. It's off to the last desperate measure of installing XP onto another hard drive in the machine, installing WoW and trying to get it to reboot. If it does, then the only thing left that is the same from the old computer is the video card.
And it's not a cheap one. . .