The 8800GTS is a lot better than the GT you have, that's for sure. It's a pretty good card and should handle anything you need to play, including Crysis, given that you aren't bottlenecked by the CPU.
I don't think they released that yet since they just came out with the 9 series cards a few months ago. I might be wrong, but ATi and nVidia are battling eachother badly this time.