Ok so I run my i970 (12 thread) on windows but then its also running 3 GTX470's
For the dual jobbie, I run also on windows, been hexperimenting (sic) with Linux but as its dual purpose need Linux to be able to do the same things Windows is doing at the moment. (VMware Server 2.0) and when I tried with Ubuntu I just couldn't get the VM's to fire up.
I guess I am maybe 25-30K down on potential PPD for running windows rather than Linux on the SR-2, I am going to try again soon if I get a chance.
For the 970, I dunno, running wine/linux with that setup is probably just too much faff for me to bother with to get the extra (maybe) points.
If I get the opportunity that one is going multi cpu bigadv and I'm going to get rid of the gpu's but I don't know when I will get the chance to do that.
The only thing I run VMware bigadv is my 2600K which is pulling 50K on a 6901 at the moment

more than the i7 970 is pulling (but then thats also draggin three fermi clients along with it)
Hope this helps.