I decided for the BF3 release coming up to upgrade my graphics card from the 8800 GT to this one, well I got the sapphire version but it is similar to this.
There are some good deals there for cards, but my budget is wifelimited so this is what I can do. :)

http://deals.woot.com/deals/details/1081cc74-36d5-497f-a135-0c5cd8700d58/gigabyte-ati-radeon-hd6870-1gb-pci-express-video-card-shogun-and-deus-ex#1

That's a pretty good price, but I would have to suggest a 2gb card.  With x-mas looming, there will be many good deals to be had in the next couple months.

Though if Bf3 is anything like BC2, it'll be more dependant on stronger CPU. And that card is still a pretty nice jump from your 8800gt.

Have you looked at what you can get for the same amount on the Nvidia side? Both companies make great cards, overall.

I upgraded a couple months ago to a 6870 and it is a nice jump from a 5770.  I can play BC2 maxed out now without problems and should be able to stay that way until I can get a new board for xfire.

I did purchase a 2G 6950 before the 6870.  It worked great for a day but then took a poop and had to RMA and so I settled for the 6870.

The 6950 was a bit overkill as the 6870 was 100 bucks less and did the job just as well.  So unless your not planning on xfiring down the road, pushing multiple monitors, or pushing mega pixels, the 6870 will be great.

I looked at the nVidias, however I decided to consult my hardware guru friend.
According to him, the 1 vs 2 GB does not matter so much. Looking at the range I am looking at to pay, the cores that the 1GB has are quite a bit more than the 2. But hell, I am totally overwhelmed at how much hardware is out there, and what will work.
The 8800 GT I got when the 9800s were out, and it has been good to me. I do pretty good with BlackOps and that ultimately is what I am looking for. Having a good gaming experience. I am hoping that this card will serve me well with BF3 until the next game comes out and BK will support it