I'm on the verge of jsut paying Geek Squad $200 just to fix this issue. I don't even know what it really is besides it being either my RAM, CPU, or power supply.
Ok, before you spent 200 bucks you can try some harmless things:
Since Windows bails out during installation already, I first suspect your memory module(s) to be bad or running at wrong timings. You can try to run this RAM test program for a couple of hours: Memtest86 from http://www.memtest86.com . (You'll need to copy it onto a bootable floppy or CD first)
The other thing to try would be to reset the BIOS to it's defaults (best assisted by someone with some knowledge on that), but I would try to test the memory first.
If all that fails, swapping out CPU and PSU with some borrowed parts would be the next step. But before that, you can try to reduce your hardware to it's minimums (CPU, 1 RAM module, Video and 1 Harddisk) if it isn't already that "bareboned"...
The problem could also be caused by a bad harddisk. Every HDD manufacturer has a diagnostic software for its drives, you can download and test your drive's health with it.
Maybe you're lucky and find out the bad part on yourself. Then you can spent all the bucks for a replacement... ;)
If something's unclear, come back and ask :)