That does seem a bit low but i wouldnt say your cpu is the bottleneck. 4209 is an ok score for the Q6600 being 3Ghz but i would expect more from the 9800gx2 at those clocks, probably nearer 16-17K. How fresh is your install? I usually find that the score can drop from a small amount to quite a substantial amount depending on certains things and i usually do benchmarks after installing a fresh vista.
I wouldnt be too bothered by the benchmark score anyway, as long as the games run fine like you say. Just start to worry when you get frame lag ingame.