Server + game on same machine, different cores?

I seem to have titled myself out of a post :D

But, would it be possible to run a dedicated server install on one core of my CPU and play a joining client game on another core? I note that in one of my most demanding missions, that FPS slowed down but that my CPU never went above 25% useage.

Set the affinity of both processes in the task manager. I would only use this for testing purposes, never for actually playing.