As I said in another thread about this a minute ago the problem I ran into with Ubuntu (and debian and mint) is that they didn't support my multi-gpu cards and so I couldn't even get through the install. I've found Centos to be a solid choice for mining multi-multi-gpu cards.
Yeah i read that, downloading CentOS 6.0 iso atm.
The setup ill try this on is a 6950 x2 and a 6870. If it works i might change the os on the main rig (580x3 & 6870).