Not my doing - this is the hard work and effort of Phil (HTTP404) on here.....
I've an edge 605 which is brilliant, but the basemap is the equivalent of using a sheet of sandpaper for a map of the sahara (boom boom)...
But the garmin topo maps are very expensive..
After some net trawling, he came up with some decent info on how to get detailed maps legitimately for free. Essentially:
1 - buy a 2 gig micro sd card
2 - create a folder in it called 'garmin'
3 - click here and download the 210mb file
4 - unzip it
5 - copy the file GMAPSUPP.IMG to the newly created 'garmin' folder on the micro sd card
6 - put the card into the unit, turn it on, et voila........
I can claim little credit for all this, just letting the masses know - it seems the chap (Andy someone..) who created the maps from "open street map" deserves a fair chunk of thanks!!
So, enjoy me harties!