Blaaagh.. I hate this!
Tried installing virtualbox on a Compaq C700. The install went flawlessly. I even tried out some stuff on it. All was well... until I had to switch on my wi-fi that is. Just wasn't showing up. An ifconfig -a showed up only eth0 and lo. Googled around a bit. Seems as if madwifi (the wifi driver) and virtualbox don't go very well together.
You can take a look at this ticket.