Originally Posted by auskip07
Because Tom Tom and all the other navigation units work off DVD?
Not exactly. Data is data, weather you get it from a DVD or an SD card. I have a Zumo 550 that I use primairly on the motorcycle. Some time ago now, the map data increased to the point that a complete map no longer fits on the internal memory of the unit. All I could get is 1/2 of the US. Top half, bottom half, Eastern half, Western half. (Slight variations based on road density). I have been loading the updated maps to the SD card for at least two years now on that unit. A Garmin map of the US, Canada, and Mexico is a little over 2 gig. When I load a new map, it finds it and uses it. On the Zumo, I also have plenty of music loaded to that same SD card. It all works. It takes that unit a little longer at startup to put the map on the screen, but works fine.
edit: Having a complete map is important to me as I have traveled much of the USA and a little of Canada on two wheels. There have been times where an incomplete map of the US would have been undesirable.