virtualbox.org

Greetings,
I was wondering if I could install and run VirtualBox from a usb thumb drive, this includes installing and running xp, vista, win7 from the thumb drive.

My goal is have everything on a 128gb thumb drive, Sun virtualBox and several installed vms. I want to have the exact same environment to use on several different computers, all different flavors of windows.

Not possible since you need to install the VirtualBox program on the host.
You can however store the VDI files on the external drive.