Linux Mining BTC

Hi, i need a little help. My brother has invested in a GPU miner, just 2 graphics cards, a Radeon 7870 and a 6850 and he is running Ubuntu 13.04 64bit.

He seems to be having a large amount of trouble finding a working combination of Linux and AMD Catalyst drivers and has crashed it numerous times...

He had it working so that the 6850 was mining, but CG miner was not picking up the 7870. Then when it did, it would give invalid nonces

After many failed reset and reinstall attempts he is getting a little frustrated with the miner, obviously with the difficulty rising each day he would like to get the rig setup ASAP so he can start working off his investment..

Has anyone any prior experience with Ubuntu rigs, and if so would they be kind enough to share how they configured and ran their miner, and perhaps if anyone has any insight into the best OS to run for mining it would be very helpful. I did find an OS built for Bitcoin mining but it seems the project died along time ago and I was unable to find a copy of it.

If anyone has a good guide they could link us to, or explain how we could set it up we would be very grateful

Thank you in advance

Luke