I couldn't run any game under wine either without crashing, even older games that usually run ok like Baldur's Gate 2. The open source driver are much more stable but on the other hand they are MUCH slower. Like, turning a good, midrange card like the Radeon 5770, into what low end crap would do in Windows. But you're better off with that mid range or a high end card since a low end card is not going to be usable at all for anything that makes use of the GPU, with the open source drivers running even free games like Xonotic on a low end card is plain crazy.
http://www.phoronix.com/scan.php?page=article&item=amd_r...
On a game like Warsow, the difference between the open source driver and the catalyst can be as high as 34 fps vs 374 fps (34 fps is not enough for a fluid gaming experience, you need at least 50 to 60. Gaming is not like the 24 fps of motion pictures with each frame blurred giving the illusion of movement even with a low framerate since each frame rendered in a 3d game are sharp as hell.) on a high end card, and 17 fps vs 45 fps on a low end card, which means that the game is not playable at all on the open source driver, while it's tolerable on the catalyst.
AMD's stuff is not worth the pain. Don't buy AMD unless you have a masochist streak. I wish I had known before I built my desktop, I was being influenced by all the free software maniacs who were praising AMD to heaven because of their policy on giving out the GPU specs. Free software be damned, I will take nvidia's closed source driver over shit that is not working the next time. My previous GPU was a Nvidia Geforce 7600 GT and it worked like a clock.