ATI Stream Processors are much more than Nvidia, but the difference is that Nvidias have more power, eg Nvidia has much less Stream Processors but they each have their own clockspeed as for ATI has a giant clockspeed for many many Stream Processors to share. Its just a different way of getting the job done. Tbh, both are fantastic, however with the Nvidia issues right now Id reccomend ATI, also because every single one of my ATI GPUs still work, and ive had 4 nvidias that all have died. But that could just be my experiance. But I do know that ATI handles high resolutions well and AA. Also ATI is cheap and good, So yea Id reccomend a GTX 260 c216 or a ATI 4870. Since your leaning ATI go for the 4870 it will save you quite a bit of money and its a great card.