WinAFC -
http://affinitychanger.sourceforge.net/It's not my program, but I find it VERY useful.
This will keep all of your miners on one cpu, and not keep your other cores running at 100%.
Since I have a 6core workstation, having 4 miners open ties up 4 cores. Not anymore.
Less CPU utilization also equals less power consumption
My config file for demonstration:
E:\Program Files (x86)\GUIMiner\guiminer\phoenix.exe := CPU1
E:\Program Files (x86)\GUIMiner\guiminer\poclbm.exe := CPU1
Enjoy!