I've got an old and basic Garmin eTrex with a serial to USB converter lead.

This works well with my copy of Microsoft Autoroute 2003 for showing where I am on a large scale map.
When travelling in the camper I like to have a dedicated GPS for turn by turn instructions and a PC with a much larger scale map to see where we are in relation to the rest of the country.

I have the NZ maps for my TomTom GO 930 but strangely my European copy of Autoroute doesn't cover NZ.

So is there an application (or set of applications) which will allow me to download maps for free (perhaps from Google Maps) and then show my location within NZ on these maps?

This would hopefully also allow me to view maps offline for route planning where I don't have an Internet connection.

So, basically, can I put together something similar to Autoroute from free components and use them with my eTrex?

Cheers

LGC