this 3dmark vantage score look right?

That looks alright, though it's hard to tell if your CPU score is right or not (that CPU score is boosted a ton by the physx acceleration on your card). My 4870x2 gets about 15000 GPU score though (performance preset), so 10000 is in the right neighborhood for an overclocked 260.
 
Not really. If you're really unhappy with the performance, you could always get another 260 and SLI, but I don't see anything to tweak right now. Does it play all the games you want pretty well?