Are you sure it is the plugin? Or could you be using the wrong driver? Just speaking from experience
, I've screwed that up in the past. I haven't tried a UIRT in win7 so other than what I mentioned above, I can't be more help. Oh, where do you have xlobby installed on the Win7 machine, in C:\ root or c:\program files\ ? I know from experience that xAnt would not work from c:\ of the win7 machine I have, and I finally figured out how to get xlobby to work in c:\program files\xlobby\ directory structure. That could also be the issue.
On a side, I've seen your AVS post. Awesome theater setup you have.