If you need some nice Topographic maps for hiking purposes, you can download those at http://gps.maroufi.net/mapdownload.shtml.
Another good source seems to be http://freizeitkarte-osm.de/de/deutschland.html.
There are two kinds of Maps. The ones on the left side are for the use with the Garmin device. I usually copy those to the SD card in the directory /Garmin.