the one you downloaded is the gmap folder: mapsource installation, copy it in:

Windows XP:
Copy "City Navigator North America NT 2011.31.gmap" folder into
%ALLUSERSPROFILE%\Application Data\GARMIN\Maps
OR
%APPDATA%\GARMIN\Maps

Vista and windows 7:
Copy "City Navigator North America NT 2011.31.gmap" folder into
%ALLUSERSPROFILE%\GARMIN\Maps
OR
%APPDATA%\GARMIN\Maps
(or something like that all other languages)

to unlock use
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