Hi, planning to purchase a boat for curising in Lake Ontario (Canada side). Don't know much about GPS. If I buy something like the Palm Naviagator package with GPS receiver and software for the 680, I still have to buy a marine map/chart for the area I want, right?

What other packages are there? I've seen references to Garmin and TomTom, the former do have marine maps but don't know about the latter. thanks