Installing 56k USB modem in Windows XP mode

Question

I have a US Robotics 56k USB faxmodem which I need installing on my machine. I am running Windows 7 and also have Windows XP mode installed. I have searched a lot and it would seem it is not compatible with Windows 7.

There are Windows XP drivers on the USR website, so thought I would try installing it in XP mode, however when trying to attach it as a USB device I get the following error;

(I have tried both the suggestions in the error message)

I have tried the Vista driver from within Windows 7 but I got a BSOD and had to start on Last Known Good Configuration