Installing my virtual windows on an external HD should pose no issues should it with things working?

It is already a pain in the ass right now getting usb working. It knows there is a usb controller but it has no idea what to use it for and so far the instructions I have gone through just don't work.

Have to beable to use my usb devices, such as zune through the emulator.

So rants aside, if and when I get usb working will the windows virtual work just as well on an external drive that I would just move back and forth between laptop and desktop to free up the space that having 2 OS takes up?