Convert VirtualBox image to Xen image
http://www.ioncannon.net/system-administration/80/how-to-transfer-linux-from-virtualbox-to-xen/
http://forums.virtualbox.org/viewtopic.php?f=1&t=18560
http://jeremy.zawodny.com/blog/archives/010184.html
http://keithyau.wordpress.com/2008/12/05/47/
