HowtoMatrix

VirtualBox’s guest additions provide better display drivers, mouse pointer integration, seamless windows, and more. If you’re doing much work in a virtual machine you should have them installed.

VirtualBox 2’s guest additions have been improved over older versions. I wrote a guide awhile ago for VirtualBox 1.5.

I wrote this guide with VirtualBox 2.0.2, and tested both Ubuntu 8.04 and 8.10 alpha 6. (As of VirtualBox 2.0.2, Ubuntu 8.10 guests will now work.)

Read more at Tombuntu