As you know, VirtualBox is a kick-ass virtualization software. Installing VirtualBox on your Ubuntu 12.04 Precise Pangolin or Ubuntu 12.10 Quantal Quetzal is not an difficult task to do.
If you follow the steps in this tutorial you will manage to install VirtualBox succesfully on your Ubuntu System. The tutorial works for both Ubuntu 12.10 and Ubuntu 12.04.
Step 1. Add a new file to the apt sources
$ echo "deb http://download.virtualbox.org/virtualbox/debian $(lsb_release -sc) contrib" | sudo tee /etc/apt/sources.list.d/virtualbox.list
Step 2. Add the repository key to your trusted keyrings:
$ wget -q http://download.virtualbox.org/virtualbox/debian/oracle_vbox.asc -O- | sudo apt-key add -
Step 3. Update the system:
$ sudo apt-get update
Step 4 and Final. Install VirtualBox:
$ sudo apt-get install virtualbox-4.2