VMware allows you to run one or more virtual machines at the same time on one computer. You can download VMWare Server for free.

It was dark when I woke. This is a ray of sunisnhe.

Installing VMWare ESX server

After installing VMWare ESX server, set in /etc/ssh/sshd_config

PermitRootLogin yes

TroubleShooting

If you get a pop-up saying "Failed to initialize mouse-keyboard-screen control", you have probably tried to start your virtual machine in an nx session. Better use a vnc session.