There is software that you can download for free that let's you use other computers on a network as second monitors...
It also let's you support more then two monitors. I had 3 last time I tried (2 hooked directly to my computer and a 3rd one on a second computer).
BTW The second computer doesn't have to be very powerfull.
And all you have to do to get back to your laptop is disable the second monitor on the main computer (right click desktop>proprities then go to settings and uncheck extend my desktop to this screen). All this is is a program installed to the laptop that sits in the system tray. So if the desktop isn't extended you get the laptops desktop.
BTW The software I found also let you control the second computer from the main. You would have two seperate desktops but when you slid the mouse to the edge you jumped in to the other computer and you could control it using the same mouse and keyboard.
This is a page from microsoft but if you scroll down a little it shows how to use a laptop.
http://www.microsoft.com/windowsxp/using/s...p_multimon.mspxBTW The program I was talking about is maxivista. You can download a free demo but you can also buy it for 20$.