First of all I changed my card for a GTX 460 but that wasn't the core of the problem. Yep I was indeed running it in opengl. What I did then was install d3dx9 using winetricks, delete my WoW config.WTF file and restart the game. I can now set almost all graphics to Ultra, except liquid quality which is stucked to Fair. I'm pretty sure this is a directx9 related issue since (I think) dx9 doesn't support shader model higher than version 3 (and that option requires 4 or 5). Anyway except for the liquid quality detail, everything runs perfectly now. To my opinion so far, wine d3dx9 is much better than opengl as far as WoW is concerned.
