How to Install Virtual Box 3.1 in Ubuntu 9.10 karmic Koala

VirtualBox is a powerful x86 and AMD64/Intel64 virtualization product for enterprise as well as home use. It is  freely available as Open Source Software under the terms of the GNU General Public License (GPL). VirtualBox runs on Windows, Linux, Macintosh and OpenSolaris hosts and supports a large number of guest operating systems. You can test your Alpha and Beta releases. It supports USB and Serial Ports.

VirtualBox-ose is available in Ubuntu repository by default but it will not support USB

How to Install VirtualBox  is Ubuntu

First You Have to add the following repository

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

For This, you have to add the above line to /etc/apt/sources.list

$sudo gedit /etc/apt/sources.list

OR

Open Synaptic Package Manager --> Settings --> Repositories --> Other Software --> Add

Now Type the following Line in a Command line

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

$ sudo apt-get update

$ sudo aptitude install virtualbox-3.1 dkms

After asking some normal questions

( Creating group vboxusers  press OK  then Kernel Module installation press Yes )

Now VirtualBox is available at menu

Applications > System Tools > Sun VirtualBox