Install Headless Virtualbox 4.1 on Ubuntu 12.04 LTS Precise

This is assuming a 64bit install and the latest versions as of 7/7/2012

sudo nano /etc/apt/sources.list

add this line to the end

deb http://download.virtualbox.org/virtualbox/debian precise contrib

wget -q http://download.virtualbox.org/virtualbox/debian/oracle_vbox.asc -O- | sudo apt-key add -

sudo apt-get update

sudo apt-get install dkms

sudo apt-get install virtualbox-4.1

wget http://download.virtualbox.org/virtualbox/4.1.18/Oracle_VM_VirtualBox_Extension_Pack-4.1.18-78361.vbox-extpack

sudo VBoxManage extpack install Oracle_VM_VirtualBox_Extension_Pack-4.1.18-78361.vbox-extpack