A few people have asked me how to install maps to their Garmin 60CSX. It is actually easier than one might think. I am on a mac (it is just as easy or easier on windows). You need to have MapManager and MapInstall both installed on your mac to import the map file to your computer and then install it on your GPS.
Go to GPS File Depot, GPSFileDepot - All U.S. Garmin Compatible Maps
find the state and particular map that you want. Download it, for the mac it downloads a gmapi file. When you double-click the gmapi file it will automatically import it into MapManager.
Connect your GPS to the computer now with the USB cable, open up MapInstall, select the map set in the drop down and choose the maps that you want to install. I usually select all the ones for the state or map set that I downloaded and then click install.
That is it.