What I did to fix it was build multiple packages for the ATI driver package and the 'Ubuntu/feisty' one worked for me. Since I haven't worked with it in quite a while, i'm getting a little rustier than I was before.
The best info I can offer that solved it for me is to try the feisty driver package, and if that fails, try the other Ubuntu related ones, they seem to be the best options (because mint is built off of ubuntu obviously).

I ultimately gave up on running WoW with it because of rendering issues, Certain terrain objects wouldn't load right, for instance, the portal on the WoW log in screen was gone, kinda odd... even more odd once in game, but that was for me.

Hope that solves your problem.