you left out the most important piece of information necessary to recommend a graphics card to you. what sort of games do you plan on playing? are you going to be playing oblivion on a 1080p screen? or do you just want a better card for guild wars?
anyways, (in general) you got the card that I'd recommend in that price range. (and purchased for myself a few months ago)
however, the downside to it is that it only has a 128-bit memory interface. (this makes a VERY BIG difference, and is heavily overlooked)
but the only way to get 256-bit in our price-range is with the 6800, where all the other specs will be lower, (less pipelines... lower core clock speed...) which is why I decided to get the 7600.
modern games don't need any more than 256mb for optimal performance.
now, I suppose the theory is that you have fast system ram, so you can pull through the tough spots when you need to without heavy performance hits, but then there's benchmarks like this