Windows 7: Problem with installation of USB device driver...

Hello,

I develop on an application which is only dedicated to Windows XP OS and older.
In order to be compliant with newer OS, some porting development are needed and then virtualization is a good thing for our team.
But after my first tests, I encountered some problem with my USB device driver used by my application.
Under XP Virtual Machine, I connect my USB device, attach it to my VM and if I use "update driver functionnality" (in device manager panel), installation starts and after a while hangs on file copying...
I tried to activate setupapi log information in order to understand where is the problem and apparently (according to last message) XP VM is blocked on my device restarting.
My device driver (its installation and running) works fine on XP, but don't work on VM with Virtual PC Beta version.
Have you got some way of research? I don't know if problem comes from my sys file or from beta version of Virtual PC.

Is there a way to attach automatically USB device in VM ? this feature would be very helpfull when you launch XP application directly from Windows 7.