Here are the specs for my crack top that most people say wouldn't run Fallout 3, and it did at high settings.
Windows Vista Home Premium.
Processor: Intell Core 2 cpu. 1.73 ghz, and 1.73 ghz.
Ram: 2 GB
System type: 32 bit.
Graphics card. Nvidia Geforce Go 7900GS.
If you have any recommendations, or questions let me know.
I have roughly $500 bucks, I can put into this rig, assuming I can find somebody to install the components.