I had nothing but trouble trying to get two Ubuntu VM's working together, even when they were working, they required constant attention.
My main rig should be able to pull 10k ppd with two linux clients and the GPU2, if the linux SMP clients actually folded for more than a few hours at a time.
The GPU is so stable, I've yet to have a problem with.
Offtopic: What board you on to get 3.6 GHz?