I have tried a couple of GPS's and the Latitude and Longitude readings I get are different than those that show up under MapPoint or even Streets and Trips.
The GPS says I am at Lat 42.14965N, Lon 84.06055W
MapPoint says Lat 42.24933N, Lon 84.10100W
(the differences are the same whether the GPS is connected or not.)

Why the difference? The GPS is Magellian Meridian Platinum using WGS84

The other GPS I referenced was a Garmin etrex and gave coordinates similar to the Magellan.

Thanks