This is how I work using two tablet PCs and one external monitor.
In Japanese: 職場ではこんな感じでプログラミングしてます。
The one in front of me is a x61 running Linux; the other one (connected to the large 24 inch monitor) is a windows xp machine.
In the video, I'm showing the perfect synchronization between those two physically separate computers with different OS's.
Usually, I use keyboard to emulate mouse movements, so you might find something unusual in the vid.