What video card to get for Skyrim?

I've got a Phenom II X4 965 BE edition and a 6850 in my gaming rig now. I'll be getting Skyrim (and maybe BF3), will play on a very nice 1080p projector (not some cheapo LCD monitor), and want Skyrim to look good, so good it'll make all my Xbox 360 friends jealous (maybe converting them to PC gamers). Got an 8x crossfire capable motherboard, a good case, a Corsair TX750 that can dish out as much power as I need, and don't mind modding or installing aftermarket coolers if necessary.

The upper limit to my budget is probably $300, although I would prefer to spend as little as possible. A 6850 probably won't run either game with all the eye candy turned on, so, what should I get?

The obvious choice is a 2nd 6850, for crossfire. Reviews indicated the cards are on par with a GTX 580 when in crossfire, but there is one problem I fear: microstuttering. I hear it can be pretty bad on crossfired or SLI cards, making 50 fps look more like 20fps. Is it as bad as people say?

The second option: Get an enthusiast card from ebay. I've seen a few used GTX 480s, 6950s, or 6970s on ebay for a good price, often under $300, some with aftermarket coolers. But would getting a used card without a warranty be worth it? Would the performance boost be good enough?