Atomic, I use one exactly as you described.
I have two pc's and two monitors. The second monitor i have is switched between being used as a second monitor for the DAW and the primary monitor for the server pc.
One mouse and keyboard for the lot though! Very tidy.
Make sure if you get one that you get the good ones. I.E. the ones that switch electronically, not the ones that just use mechanical switches otherwise you risk system lockups and won't be able to use keyboard/mouse system startup up etc.
This is the one I use:-
http://www.rextron.com/html/product/k102.htm
It's very compact, allows instant flickerless switching, keyboard/mouse startup feature on your motherboard still works, and it has been very reliable for me.
Cheers!