I have successfully installed Virtualbox in my Ubuntu Feisty Fawn desktop. Installation was pretty simple. Im listing the steps I followed to get it installed and configured.
Read it at Aruns blog
Go to Virtualbox download site and download the binary file compiled for your OS. I installed it on Ubuntu Feisty Fawn, so my tutorial is based on Feisty Fawn installation. I downloaded the binary package for Feisty Fawn from here. Open a terminal after the download is complete. Go to the folder where you downloaded the file. Enter the following command to install Virtualbox.