If you are using any kind of DVI splitter and are encountering problems where your display is not being detected (because it is now "disconnected" - aka switched) then Gefen has a neat little device that transmits the EDID data to the video card, tricking it into thinking the monitor is still connected.

This means you can turn on a computer with the switch in the opposite position and the OS will not disable the monitor, thinking its not there.

http://www.gefen.com/kvm/product.jsp?prod_id=1378

About $70 each retail.

You need 1 per port you are going to connect.

Gefen makes some DVI switches but they are VERY expensive and pure digital. Go manual and save a ton of money. You lose the ability to remote switch though, unless you extend the wires enough and use a DVI booster or hook up a custom switch yourself.