When using 2 (or more) computers it really helps a lot if you can control both computers using only 1 keyboards+mouse. I personally started by using Synergy, but since it has that nasty spinning bug i was forcer to use 2 mouse for a while. Then I bought Multiplicity and it made my life so much easier. You should look into Input Director. I would probably use that if i haven't already bought Multiplicity.

I'm using InnerSpace for multiboxing. It has really good mouse broadcasting for in-game clicks. For everything else I just mouseover to other computer and control it like it was my main computer.