There are only a couple games that benefit from more than 4 cores, and the benefit is no where near significant.
4 faster cores > 6 slower cores
Not to mention... its 32nm... Sandy Bridge... Easy choice for a gamer.
OP what resolution do you play at? At 1080p you won't see a performance difference between the two. I like to see anyone show me a cpu bench where one cpu crushes another at a high resolution.
Check out 5870 crossfire or better and you'll see significant differences (not many reviews out there) between K10 and i-core CPUs. Of course there are games that are very GPU bound or AMD favored, but the majority follow this (from what I've seen).