I am a happy owner of an Asus ENGTX 275.

So far the performance is very good. If you can jump to the 275 instead of the 260, the performance difference is noticeable.
The nvidia 260 will do a nice job anyways. Mostly depends on what do you try to push with it.

My card does 5 wows on a 24" screen without lag not screen tearing. Main is always on 55 - 60 fps except in dalaran when main drops to 20 - 40 fps.