Hello,
ATI drivers have some odd problems with mipmaps that could appear as missing textures, and last week I had a 'new' problem crop up that caused the driver to hang the system, even with old drivers on code that had been in wined3d for months so I'd wouldn't expect any kind of stability with ATI's drivers.
I've sent a bug report to ATI, and I hope that they look at it and fix the issue. I think the chances are quite good, the Linux support has really improved over the last months, and they have added support for many things now(Like suspend functionality, which came with the new 8.19.10 driver)
Otherwise, I'll try the newest development version of X.org 7.0 ;)
Stefan