There are a lot of ways to connect various Linux or Windows machines. Linux has great support for the windows remote desktop protocol (RDP) with rdesktop, but if you have second (or third) screen that can be seen at the same time as your main screen, you should try out x2vnc.
What is X2VNC
X2VNC is a software tool readily available for linux that creates a mapping between a VNC server (on any system type) and an X screen in linux.
Example X2VNC Setup
I have a two screen setup on Kubuntu. I also have a TV screen above and to the left of my two monitors. x2vnc allows me to map the VNC server running on the TV as a third screen on my main system. The first step was to install a vnc server on the computer connected to my TV. The second step was to run x2vnc -west yt:5900, which creates the screen mapping.