I came across this page today on how to get the Sierra Wireless Aircard 860 to work with Vista. I tried it, and it's working great! I am using it just now!

http://chris.pirillo.com/2006/09/14/sie ... -on-vista/

I don't think you need to install the AC8x0 Windows Vista Driver 2.0.0.21 in the first link. I did install this first, but it did not install the all the drivers. The new 3G Watcher program has the Aircard drivers with it as part of the package. I chose the custom installation and chose not to update the firmware. The 3G Watcher program finished installing the Aircard drivers as well as the Watcher program.