unbusted67,
Yes you can take your .gpx (waypoints and routes) and bring them into your Garmin 5208 or 740.
You have to use a converter ( www.gpsbabel.org ) to convert .gpx to Garmin format.
My Standard Horizon CPV350 accepts .gpx files directly via one of the NMEAports. The upload/download NMEA port is selectable within the chartplotter via the menus.