2 Linux VM's on Q6600 - Set Affinity or No?

Alright, so for a while I was folding with a single WinSMP instance on my Q6600. I finally got around to setting up two Linux VM's with VMWare server and Ubuntu x64. Each just turned in its first WU.

My question is, will it be more efficient to set affinity (Core 0 and 1 for one, Cores 2 and 3 for the other) even though I use the computer, or leave them unrestricted? Currently, there is a noticeable difference in frame times between one instance and the other - ~15-17min per frame on one, 19-23 min per frame on the other. Obviously the times will be slightly more equal if I'm not using the computer, but there is a discrepancy.

Anyway, having only limited understanding of the benefits of Affinity and SMP - should I set affinity, or no?

Windows is not the best at process management. You will gain some ppd and should not lose any interactivity of daily use by forcing affinity on the vmware threads, bonus if you can keep the two threads on the same core due to separate core L2's.

Run with affinity as you described. 125 ppd increase on a Q6600 @ 3.0 GHz.