From the Minnesota DNR web site:
This extension was built to provide users the ability to directly transfer data between Garmin GPS handheld receivers and various GIS software packages. Using this program a user can use point features (graphics or shapefile) and upload them to the GPS as Waypoints. Line and Polygon Graphics or shapes can be uploaded to the GPS as Track Logs or Routes. Conversely, Waypoints, Track Logs, and Routes collected using the GPS can be transferred directly to ArcView/ArcMap/Google Earth/Landview and saved as Graphics or Shapefiles.
This program has a real-time tracking mode that allows users to follow their progress on the ground within an ArcView View Document, ArcMap Data Frame, or Landview Map. This real-time track log can be saved as either points or lines as a set of graphics or in a shapefile.
Click here to go to the DNRGarmin web site