There is a program called ProLasso (Project Lasso) that allows you to set default priority and affinity for any task. Maxwell uses this also and it is FREEBIE.
I set my Moo and PG wu to run on and only run on threads 6 and 7 (core 3 of my I7). I also raise their priorities to HIGH. Then I assign whatever I'm crunching CPU to threads 0-5. That way the GPUs have their own unobstructed core to use.
I HIGHLY recommend this program!!!!!!!!!!!!!!
Process Lasso. Don't let the thing fool you - you can use it for free. I'm loving this thing...