MaxiVista is out with their new 1.5 version. This new version has a few bug fixes, but also supports up to THREE secondary displays via three other PCs. If you've got other laptops or Tablets around, you've GOT to try MaxiVista. Don't confuse it with ShareKMC or VNC.
This is a SOFTWARE DISPLAY ADAPTER that shows up in your Display Properties. Treat it like any other monitor. Here's my setup. It's pure sex.