I bought a Garmin 18 USB about a year ago; it came with driving/map software.  I didn't look at the software very close; the first impression was not that great.  I have MS Street and Trips (2006) and really like what I see (not what I hear - because the voice is not loud enough to hear - I need to get an external speaker).  I use the Garmin 18 USB but it will only transmit Garmin's strings.  I bought Franson's gpsgate software and have been very satified with it as it converts the Garmin strings to NEMA strings that MS S&T needs.

MS S&T has a feature that allows you to create a path/map showing where you have been.  That is great as someone often needs to make that same trip again; it nice to be able to just show them a map with route, or better yet, send the laptop with them and just let it show them the way.

I have found places where MS S&T shows roads where there is not even a cow path.