I have an AMD Athlon 64 3000+, 2.01 GHz. 1GB crucial balistix RAM. Geforce 6600 GT GFX (I don't think a high end card is that neccesary for emulation in MAME, although I might be wrong). I've had no probs whatsoever with this setup. I'd recommend you go for an AMD CPU, gig of RAM minimum, and a midrange gfx card.