x850xt is the main option.
When i play a game i want good performance and decent visuals. 7600Gt is good now but it'll get weak as time goes and will be unable to handle some of its features(like FX cards have problem with 2.0 pixel shadders in most games or x800 don't support HDR i think?). X850 delivers much better performance and as said before handles AA and aniso much better. Go for it.
People need to stop thinking of it as a 6600GT and realize that it in fact does beat out every high end card from the previous generation despite its 128-bit memory and 12 pipelines. Some people are just having a hard time accepting that I guess.
I don't use the dual slot cooling as a factor. I car about getting good performance, so dual slot cooling isn't an issue. Yes, X850XT needs extra power connector, but it isn't an issue. 7800, X1800 and X1900 all use extra power.X850 takes a 2 slot cooler and needs 400 watts of Pure Power.
7600GT is a single slot solution and Needs No Internal Power connection.
X850 Prices on the internet are so low, they're practically givin them a way. X850 is also yesterdays news with no SM 3.0 support.
7600GT carries most feature sets from the 7900 series, yet they are almost cut in half (you can read that somewhere).
128 bit, full path, studio precision interface carries a bit more muscle than you will be led to believe, but at higher resolutions that x850's 256 bit face will definitely make a difference, but if you're like me and play most games at 1024x768, then the little bit path doesn't make much difference.
It all depends on whatcha want.