They are currently one of the best Price/Performance ratios, and should be pretty good for gaming. They'll also be great for mining. Can expect ~360MH/s (SHA256) or ~360KH/s (Scrypt). I plan on buying some of these when I upgrade from my 6850s. And yes, mine with your PC when not using it. I leave my gaming PC on 24/7. When I'm sleeping or working, they are mining.
EDIT: Maybe some 7950s if you really need the extra performance.
I have 2 Asus ones. That is the only thing, buy goddamn Asus ones, they clock much higher and the DCII cooler is a beast, 45% Fan and 55-60 degrees @1165 core, 1500 mem, and the best thing is that they are undervolted (-0.1 volt) at those golden clocks, I can reach 1300 mhz core and 1550 mem on one cards with a 0.1 overvolt, but don't want to stress the cards too much, at those clocks they reach 450Mh/s/450Kh/s.
Edit: Gaming is no problem, 130+ Fps in CFX, 65 Fps single on Battlefield 3 Ultra +AA+AF @1080p
The crossfire setup chews Metro LL At 50-60 FPS ULTRA! (Which would normally take you a 690 or higher). This is in an overclocked state