December 11, 2008 10:39 PM

There is a thread here on the site (I believe it's called "OK I need a second monitor") that mentions a USB-based product by EVGA, the UV Plus+ (UV-16) adapter. Check out http://www.evga.com/articles/409.asp

The key is that you have to find something that has 64-bit Vista drivers. Apparently the above does.