My wife is playing @ 1440x900 resolution with a GTX 260 (similar to 8800's in SLI). She plays at Medium settings fairly well. She also has a Q6600 CPU, but it's overclocked to 3.2Ghz.
The CPU seems be become a limitation to the video card as Skyrim forces the CPU to render Shadows. So you might adjust the Shadow level (Low, Medium, High, Ultra) and see if this helps with any performance issues if you have them.