I am what you would probably call a casual gamer. Maybe I'll fire up a game once or twice a week or so.Anyway, the common error is to use wine incompatibilities (before wine 1.2 and fglrx 10.5 XD) with ati to blame ati opengl 3d performance. This is just ignorance.
In this specific case it's Homeworld 2. A truly marvelous 3D RTS. The thing is, I never did finish it back in the day so I thought I'd give it a whirl. On my 8800 it ran supersmooth. It was a joy to play. Unfortunately, it's not so on my 4870.
I'm not laying all my blame on AMD. They have clearly improved their driver a lot the last few years. But the fact is that they have been so far behind for so long that even with their huge improvements, they're not quite there yet.