VirtualBox is a virtualization software you can install other operating systems within operating systems. It currently supports operating systems install GNU/Linux, FreeBSD, Windows, Solaris and others.
To install on any version of Ubuntu to natty:Note: Ubuntu based distributions that do not retain their codename as LinuxMint change `lsb_release -cs` by the version in which the base (jaunty, maverick, natty ...)
Add the repositories:
sudo sh -c "echo 'deb http://download.virtualbox.org/virtualbox/debian `lsb_release -cs` contrib #Virtualbox' >> /etc/apt/sources.list.d/virtualbox.list" && wget -q http://download.virtualbox.org/virtualbox/debian/oracle_vbox.asc -O- | sudo apt-key add -
sudo apt-get update
And install virtualbox:
sudo apt-get install virtualbox-4.0 dkms
Now download and install double-click the extension pack to have support for USB 2.0.
More information: Virtualbox.org