i mean what type of memory you have. for instance... i have 4gb's of corsair XMS3 DDR3 ram running at 1600mhz dual channel kit.
if you have enough money i would suggest a top end graphics card. an ATI 5000 series or Nvidia 400 series.
i have a gtx 470 myself and there isnt a game on the market i cant run on max seetings with phys-x enabled. they are about £230 for the card