RE: Does anyone use the GPS set up that you can get with MS Streets &
Trips?

Yes, I have S&T and have used the hell out of it for several years.  And I
do have the GPS module for it and that works great also.  BUT I DO NOT try
to use it for on the road navigation.  I have tried it that way and find it
just plain dangerous if traveling alone.  It works fine if you have a
'navigator' on board, someone in the passenger seat to use it.  I suppose
that with the right laptop and the right mount it could be used, if careful,
while on the road, I know some do.
I find S&T great for trip planning and the map files seem to be complete and
the POI files okay.