What are you talking about? Why are you using Google maps when Nokia give free point to point Sat nav for free to the phones that can support it? Plus Nokia Maps has always been able to run from a stored cache of maps. I used to do exactly that with my N95, and I still do it with the N97.
Unfortunately the GPS on the N97 is so f**king bad it looses track of you the moment you move above walking pace, assuming it can even lock your location in the first place!

This thing looks like something from the last decade. Wake up nokia, I want GPS with a phone that has stored maps so I dont get that crappy moment approaching a junction when google maps decides it doesnt want to show me the map. I'm stuck with you until Android gets its act together.