After I purchased my Garmin 76Cx I went to the Garmin Support page and signed up to received automatic e-mail notification of software updates for the 76Cx. Shortly before I received the replacement unit I was notified that there was a software update. I believe that the 76Cx manual the manual for my other Garmin units could do a better job of describing the software updating process.
I wanted to make sure the new unit had the updated software installed. I suspect that it had been on Garmin Support unit shelve for sometime. And it was unlikely the latest updates had been installed. Your might find the same thing if you just purchased it from a vendor. I went to the Main Menu Page, and selected the Setup Icon. I then selected the System Icon and hit enter. On the System Page I hit the Menu key. A popup window gave me the Software Version option. This gave me the versions for the Software Version and the GPS SW Version, and the unit ID number. I went to the Garmin software updates page and found that I need to download updates for both sets of software.
http://www.garmin.com/support/blosp.jspI have a rather thick skull but I feel the Garmin Unit Manuals fail to properly address updating unit software. It was not unit I checked the software version on my unit did a light go on that I may have to download two different sets of software for one unit. This was confirmed when I check the updates for my 76Cx. Your will also find this true for the 60Cx, 60CSx, and the 76CSx.
If you have a mapping gps or a gps that will connect to a computer you might want to check the manufactures support page for software updates.
One of the recent updates for the 76Cx allows it to recognize up to 2025 maps. That might take a 2 GB Micro SD Chip.
MAKE SURE YOU ARE INSTALLING THE CORRECT SOFTWARE IN YOUR GPS. IF YOU INSTALL THE INCORRECT SOFTWARE UPDATE YOUR UNIT WILL FAIL, AND YOU WILL NEED TO RETURN IT TO THE MANUFACTURE.
http://www.magellangps.com/support/