I've run ATI cards (all made by Saphire) for years. (7000 , 9600 9800)
The 9600 SE I had was a bit slow until the major rewrite by ATI of there Catalyst drivers.
I now run an 9800SE and have no probs at all. I run catalyst 6.6 drivers and get a smooth performance (apart from a little slow down when water blurs the periscope)
I am supprised to see ATI being critisized in this thread, I think they are fine. My next card will be an X1900 ... when the wallet allows.