Install Virtualbox-3.1 on Debian

1. prepare the environment for build kernel module of virtualbox

sudo aptitude install module-assistant dkms
sudo m-a prepare

2. add repository of virtualbox for debian lenny

deb http://download.virtualbox.org/virtualbox/debian lenny non-free

3. get the Sun public key for apt-secure

wget http://download.virtualbox.org/virtualbox/debian/sun_vbox.asc

4. add the public key into apt

sudo apt-key add sun_vbox.asc

5. update the apt repository

sudo aptitude update

6. install the virtualbox

sudo aptitude install virtualbox-3.1