Do you put both these drivers in the RAGE directory, or only one, because your post is lacking that information?
I tried putting each one in there separately and together and together is not a good idea. Per my setup I got the best performance using the x64(atio6axx.dll) file.
My setup at a glance:
Win 7 64bit
Crosshair IV Forula Mobo
Athlon Phenom II X4 965 quad core @3.6ghz
8 Gigs Kingston Hyper X RAM 1600
Corsair Force GT 120 GB SSD
Sapphire 5970
3x Acer 24" monitors @ 6048x1080 - Eyefinity
Game was finally running pretty well for me up until I hit the Dead City and now I am seeing the texture popup thing again which is annoying. Going to finish this game in time and then uninstall it for Skyrim.
I'll be shocked if they do another patch before December. What a way to disappoint Carmack...