Funny. I had WoW running on a 5100 Nvidia card using envy to install the graphics driver.
Turn Compiz off that's a big help.
I installed the latest Wine from Wine HQ, and followed the help given at the following link(s) to edit the Config.confused file, the winecfg file, and the Wine Registry. http://www.wowwiki.com/Linux/Wine
look at the Troubleshooting and Misc links from this page as well.
Since you started on Ubuntu you'll know this sight:https://help.ubuntu.com/community/WorldofWarcraft
Lastly, believe it or not there is an add on called "Apply Directly to the Forehead" that helps in some cases.
It will work, I have it running on Daryna with Nvidia 6800GT, and Daryna with 7600GS and Elive on same machine.