Anthony,
First the good new, the Garmin is a nice unit and the Maptech software is great. Now the bad news, you can only upload Garmin mapping software to a Garmin GPS. You can create routes on the Maptech software and upload them to the GPS. You can save tracks from the Garmin GPS to Maptech maps.
You’ll need to buy the Garmin, Mapsource, US TOPO 24K, National Parks, East to load the topo maps into your GPS. This version has all the topo for the AT from GA-ME. With 56 Mb of memory you’ll be able to save a large map set onto the GPS. For the hell of it, I own this map set, I figured you can save all the topos for the AT from Waynesboro, VA to Katahdin. This should mean you’ll have to have access to your CD and a PC/ laptop to replace the maps with the next section your working on. These maps will load in addition to the base map pre-loaded in the GPS.
Good luck on your hike,
od
od