Along with Call of Duty 4, it is one of the most scalable and fast running gameing engines i have ever used, you can play UT3 ABOVE MINIMUM ona 9600XT and 2600+, i tried it with my sisters pc, she got 27fps average just above minimum, i mean that is incredible with how good this engine looks, i turned it to as low as it would go just to see what it looked like, and somehow it looked far from bad, yet played at ridiculously good framerates. 8600GT will be fine, anyway this game is so fast paced you won't notice the difference between low and high