the 5850 is the best of those cards. I would seriously consider overclocking the cpu if i were you. You can get it to 2.8 ghz quite easily on stock cooler and stock voltage. many people get it to 3ghz stable without voltage increase. I would give the heatsink and fan a good clean with compressed air and possibly re-seat the heatsink with good thermal paste. I think an aftermarket cooler would be a good investment and is worth doing IMO. you can get that cpu to 3.4 ghz with a good cooler and some voltage increase without too much effort which would put it near the performance of newer equally clocked Phenom X4's. The core 2 quad is still a very capable cpu.