Is there a program that will let me draw a route on a map, and connect to a GPS?

[BiikeMike]

I am looking for something that I can draw out a route on a map, connect a GPS puck, and be on my way with turn by turn directions on my MacBook Pro. I have a Garmin Nuvi 660 and love it, but I need something I can actually pick the route for.

Any suggestions?

 

[JNB]

Didn't the Garmin come with it's own mapping software? They used to, though it's pretty crappy considering all that's out there. It still works for uploading the resultant route to the 660 (or should, anyway).

 

[Mal]

Google Earth Pro will, though I don't know if you can then download the maps to work offline.

jW