[AChimp]

Well I'm saying that if the motherboard runs at 100MHz and the RAM is 133, you should still be able to use them without changing any settings.

Only thing that I can think of is Windows doesn't like the system change (PC boots up and passes POST so it sounds like it's Windows or something Windows is loading that reboots).

If you can get a separate HD and install Windows on it in that PC, you'll know for sure if it's the software or hardware.