I have a pretty lean sys that runs STW2

Intel Core2 Duo E8500
2GB RAM
NVidia 9600 or Raedon 4850 (both are PCI Express I swap them:p)

Its a relic :) but it does everything I want it to do therefore I will drive it til it drops.
The parts were cheap when I put it together, likely much cheaper now (if available)

I doubt my graphics are the prettiest, but that has never concerned me; games play smoothly at default and it all looks ok to me :)