Second: IF you run the game in Crossfire, after the above install the Catalyst CAP 2. (Edit: then reboot)
CF or not, then download and extract this file in the Rage folder, and that's it (It has 4 dll files that goes in the game root folder, and a config file that goes in the base folder): https://rapidshare.com/files/882382613/RageFixCrossfire.rar.
I've uploaded the file myself.
I promise you, here it worked like a charm. FINALLY (at last, at last, at last!) I'll be able to play this game without pulling my hair out!
Fingers crossed, I really hope that helps you too.
P.S.: Probably the d3d9.dll is not necessary, but I guess it can help in case of low FPS (it was the one used to improve performance in Fallout New Vegas). It doesn't hurt at all having it in the Rage folder, though -- just in case.