I recently installed the latest beta drivers from Nvidia and there's a noticeable performance boost on my GeForce 7600 (DX9 Windows XP). I thought I might mention the drivers in case others here are interested, although I'm sure your nifty new 8800 GT is running along nicely as it is. ;)

Supported for these drivers are GeForce FX, 6, 7, 8, and 9 series cards / chipsets: Head to Nvidia's page for release v174.74 beta.