Is it enabled in your bios? It happens... it will see your integrated GPU from the CPU as primary GPU and just disable the actual GPU until you enable it in the bios.
Try playing it on windows based operating system. Ubutu is going to utilize opengl instead of direct x. I had slower card than that I used to get acceptable frame rates.
I tried playing wow on Ubuntu 13.10 and I had the same issue. Best bet is to get a windows OS or spend a lot of time googling and trying to find some solution.
Is it enabled in your bios? It happens... it will see your integrated GPU from the CPU as primary GPU and just disable the actual GPU until you enable it in the bios.