Synergy is the KVM software that allows you to use a shared mouse and keyboard between screens. Either they're the same operating system or not, this is a great tool to have installed. Unfortunately found that installing it on Ubuntu 11.04 is not as straight forward. You'll need to download the deb package from http://synergy-foss.org/ , then open a terminal window and install it the following way:

#sudo apt-get install libqt4-gui

#sudo apt-get install libqt4-network

#sudo dpkg -i synergy-1.4.2-Linux-i686.deb

:) All done now