I still have an old 128MB 9550XT GeCube already overclocked a bit and it kicks ass because it can render Oblivion (the outside scenes) very good (be it with all settings low and @ 800x600). Inside scenes are even better. Ok, I admit I have 1gb of ram but I only have a 2.26 P4 with no HT.
If I will buy another ATi, it will have to be Vista ready and from GeCube. I like GeCube because they don't (or at least didn't) bundle any halfassed crippled applications that don't even have suppor for more than 2 speakers. All I will find in the box will be the cables, the manual, a cd with drivers (Which I won't use because i'll get Catalyst CP from NGOHQ

) and the graphics card, of course...:P
However, I find myself fiddling around with Linux more and more and might pick up a nVidia unless AMD-ATi will have a better support for other operating systems other than Winows and OSX.