Hi Giorgio and welcome to the forum!
As far as I know, the LCD in your case is connected via VGA. The USB should only be for the touch screen function. Please, any of the HD160 XT owners, correct me, if I'm wrong.
Unfortunately there isn't a really good solution for these kind of touch screens (yet). The best one I know is to use the clone mode of your graphics card driver. However, this requires that your main display uses the same resolution as your touch screen.
I tried to collect some possible solutions in this thread:
The Ultimate Touch-Screen-HTPC-Case-Thread
cheers,
Michael