Bought myself a 3760 (and just luuuuurving the high res capacitive touchscreen!) (Thanks Tony) and have activated the lifetime free map updates on it. Fiddling with the map updater - as you do - I found an option to update just the nuvi, or just the pc, or the nuvi and the pc. Can't hurt, I thought, so I clicked it and re-updated.
I now have the latest Australia and NZ City Navigators installed in Mapsource as well as the Nuvi