I use one to switch between my desktop and a laptop in a docking station and its really nice. Most of the larger electronics supply catalogues and stores have them in different configurations. Mine is just for 2 pc's but Ive seen them for as many as six. The upside is that it frees deskspace if you run multiple computers and is cheaper than buying another monitor. The downside is you can only view and type on one computer at a time and there is a noticible delay before the monitor synchs when switching computers. Most have a button for selecting which computer your monitor, keyboard, and mouse are controlling and some can be set with a hotkey combination to switch as well. On mine I have noticed that the trackball fine movement contral isnt as precise as the other system and seems to be something possibly due to the extra cabling length required. One source is Computer Discount Warehouse (
www.cdw.com) but most of the national mail order companies carry them.