Hello,
I have a bfg6800u and play bf2. To go on any map and not have to worry about slow frame rates I have to adjust my options according and as far I as can tell quality doesn't suffer. BF2, from what I have gathered needs 2 gb of ram to run smoothly and still have consistently higher frame rates. Your 6800 gt is going to give you about the same performance as the ultra. If i had it over to do again i would probabaly get the gt instead of the ultra. I got the ultra because i found a deal thru dell. Paid $419 last Nov.
I strongly suggest that you give BFG consideration. Lifetime warranty 24/7 support. I can't give you much info on ATI but they do have a good product. Here is a poll (not scentific but take it for what its worth )
POLL
I remember the situation your in last winter... what video card to get....
just keep up your research and you will end up with what you want...
good luck
jd