After plugging in the memory stick with the gps file, you have to select "import" from the menu to load the file. It worked okay for me.
I have the Garmin 550, but the 660 is no different. If you plug the unit in, your computer should recognize the GPS as a drive. If you are using the HD Ride Planner, there is an "import" button on top of the map, you can choose "recognize my GPS", or do it manually. I never have a problem with letting the HD Ride Planner finding my unit.
A few caveats with the HD Ride Planner though;
1) if you drag the route to change it (EX back road instead of a highway) you will have to add a waypoint. I have learned the hard way to add a way point right AFTER I have to make a turn otherwise you will be navigated to the way point and then have to turn immediately after.
2) If you are doing a ride with a return route, then make your destination a waypoint (I add it as a finishing point, then change it to a waypoint after routes are completed, otherwise Ride Planner will send two separate routes to the GPS.
If you add a waypoint along a rote, make sure you zoom in on it on the web page map, sooo many times I have added a waypoint and did not zoom in and did not realize the way point was added to a side street and when leading a few bikes, a 50 yard u-turn makes you look foolish and can put others in a dangerous spot.
I wish Google Maps would wake up and allow a Garmin GPS route to be imported into the GPS unit. Right now it only brings in the start point and end pint, no detailed route