I have a Garmin 60CSX with a 2GB microSD card in it. I have full streets maps for all of the US and Canada and all the topographic maps. The topo maps don't provide great coverage unfortunately; this miss a lot of areas I'm interested in it. So, paper versions are a must and it's also not a bad idea for when you batteries (or gps) unexpectedly go kaput.
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"When I read about the evils of drinking, I gave up reading." Henny Youngman