Welcome to CSR Nation
I need step by step help I tried downloading windows virtual xp but I kept getting an error saying "cannot close comm port" and never got my machine to connect to my lap top.
I'm probably not going to be able to offer much in the way of assistance, but I would guess that you need to ensure that your USB adapter's software is installed in such a fashion that the XP side sees it. Once that's done, you'll have to see how to make the XP side override the Windows 7 side when it comes to who does what with the USB ports.
Once you figure all that out, the instructions in my "Troubleshooting" article (http://www.cheapandsleazy.net/troubleshooting.html) might be of some use … but if not … well, if you're on Facebook, there's a couple of groups dedicated solely to Case Catalyst that might have someone that might know ….
Sorry not to have THE solution, but … well. 64-bit Windows and VPC is a bleeding edge kinda thing, and I haven't heard of many attempts to do what you're doing …