Apple Logic Pro /LogicExpress Discussion

This is more a Mac question than a Logic question, but hey, that's why 
I'm on the uncensored listserv!

I have been using my newish iMacIntel as music computer, with my G4PB 
as everything else.  Fuggedaboutit!  I want that extra speed and 
elegance for everything I do.  So now I want one kvm setup at my 
keyboard, and another, dual monitor kvm setup at my computer desk.  
This requires 3 monitors, though not necessarily at the same time.

In other words, I need either a monitor signal splitter or a switch as 
diagrammed below.