When you get your 8800GTS 320 you'll probably be getting 22 to 32 fps depending on what type of CPU you have and in-game resolution you play at.. and what settings as well. If you play on all medium, there are some noticeable effects that are lost, but if you don't really care about it.. it wont matter. You'll be getting a constant 40-50 fps. You can always set some settings to high.
The one that really makes the fps nosedive is the Shader option. That thing alone will knock off 5 to 10 fps instantly. Also, the motion blur that compensated at high will no longer be in effect at medium. It will appear more smooth and also feel more smooth. But hey, I love eye candy.. mmmm