Monitor upgrade, time for new video card?

[The Pharaoh]

I am about to purchase a new monitor and I was hoping to get some input from [H] crew as to whether I'd be wasting cash upgrading video cards to go with it.

Current setup:
-Samsung Syncmaster 2232BW 22" @ 1680x1050
-HD 4850 CrossFire (OC'd @ 720MHz)

New setup:
-ASUS VE278Q 27" @ 1920x1080
-New graphics card?

When I got these 4850s they were a great deal, about $315 shipped for both the week after launch. Now it seems there are a ton of great video cards available and I wanted to get suggestions.

Right now the games I play most are BFBC2 and the new Vietnam expansion, L4D2, The Ball and Worms Reloaded. I used to be a really hardcore gamer but now I mostly work on my music productions and DJing. I still have a need to max out the games I play while stacking on as much AA and maintaining the best FPS I can. Ideally I would be spending about $200 on a new card, but if this won't bring a good upgrade from the 4850s or there is a better but costlier option I would love to hear about it.

So far I am looking at 6850, 6870, 5850, 6950 but I'm open to an NV card as well if there's a case to be made. Thanks in advance for any input.