At first glance, the numbers look terrible. But remember, this is an RTS, not a first person shooter. Consistent frame rates are more important than a high average frame rate and even 1280x1024 is playable.
Regardless, can you say "CPU bottlenecked?" Yes, Supreme commander doesn't seem to care which video card is used. There is fluctuation here and there, but the benchmark is a replay of a saved game and won't produce exact results each time it is taken, so we can conclude that the video card isn't having much of an impact here. Let's add some image quality options and try again:
Frame rates took a hit, but a relatively small one. And it's the same old story retold, as the 8600 GT has playable performance at 1024x768 with IQ options enabled.