You donīt have but must install MapSource...
First if you want to edit routes and or wpts for transferring latelly to
Garmin Mobile PC...
Also... with Mapsource installed ,in Utilities/Obtain Unit ID... it lets you Find GMPC... From now on dont even need to attach GPS 20x for transferring anythinf to GMPC.
Search in the Forum from where and how to install Mapsource
Mapsource is the other way to transfer data to GMPc...(as PoiLoader does);but as what MS transfer goes to My Favourites... the latter sends to Custom POI`s of Interrest...
Hope this lights you way...
Best wishes from Jucabras