Unreal Tournament 2004
We'll start off with the somewhat ageing, and thus oft CPU-limited, Unreal Tournament 2004. It's still a popular title however, so is always worth a look.
Without AA and AF, all of our cards find themselves CPU-limited across the board here.

With anti-aliasing and anisotropic filtering turned on, the GeForce 6600GT breaks away from the pack at 1280x1024 as the CPU limitation diminishes, while the NX6600 keeps pace with ATI's Radeon X700 PRO. The two 128MB boards drop off more sharply at 1600x1200 as video RAM becomes more important, leaving the MSI card bringing up the rear. All three boards offer a very playable experience at 1280x1024 at these settings however.