just keep in mind that ATi never got the drivers to work well with the x8** series cards...so i would be going for the 6600GT...but why not get the 6800GT ?? or even the 6800GS ??
I already have a 6600GT that I bought a few weeks, just looking at other options.
Seems like every time somebody brings up a specific video card the 6800GS is brought up...
Granted its a good card, but still.
Except you are forgetting that any games that will make good use of SM3 will run like *** on the GeForce 6 and probably even the Geforce 7 series. So that is a null point. The X850XT is much faster than any card in the GeForce 6 series in terms of brute power. But I still recommend the 6800 or 7800GS.