VirtualBox
Get the latest ingo about the VirtualBox for linux at https://www.virtualbox.org/wiki/Linux_Downloads
Python2.5 dependency
VirtualBox 4.1 depends on python2.5, however, the latter is no more in Ubuntu 11.04. The solution is to get it like this:
sudo add-apt-repository ppa:fkrull/deadsnakes sudo apt-get update sudo apt-get install python2.5
Then do the Virtual box install.
Generic install (older)
To install VirtualBox virtual machine engine in Ubuntu from the repositories:
sudo apt-get install virtualbox
Then add your user to the virtualbox group.
In case you can not start the Virtual Box machines and get a message that you should install ...modules... package, try sudo apt-get install "the-corresponding-module-package".
If you can not find the package in the repository (I could not find virtualbox-ose-modules-2.6.24-25-generic while running 2.6.24-25 Ubuntu kernel version), try the following:
sudo apt-get install virtualbox-ose-source module-assistant sudo module-assistant auto-install virtualbox-ose-source sudo /etc/init.d/vboxdrv start