Whats the difference?
I'll be using it on a 17" 1.5 PowerBook w/ OS 10.4.x. Most likely for route planning only.
If you go to the homepage of
GPSNavX there is a link to a comparison chart of the two products.
While MacENC will run on the older much slower PowerBook G4 or iBook G4, we recommend GPSNavX for such Macs.