Your wish is granted.
There's a great free (as in beer) little keyboard and mouse sharing software package called Synergy (it's a SourceForge project) that let's you use one mouse and keyboard to seemlessly access multiple systems. It's available for both Windows and Linux (and other Unix versions). There's also a partially-completed Mac-OS versions.
The assumption is each system has it's own dedicated display(s). You set up a little config file with your screen layout. When you move the mouse past the edge of a screen, instead of stopping, the cursor just continues on the next screen. ON A DIFFERENT COMPUTER. The keyboard focus also shifts to that computer. It uses TCP/IP networking to communicate between the machines, and it essentially acts as a mouse/keyboard driver on the other systems. (i.e. that your mouse/keyboard aren't connected to.
It will also cut-and-paste between computers.
Shut down a computer or disconnect it from the network and no harm done. Now the cursor just stops at the edge of the screen, until that computer comes back. (I think it will even just hop over a "missing" computer if you have more than 2.)
I've used this with my notebook, and it is a great little utility.