Totally agree. Garmin MapSource Topo U.S.
Very easy to install and use. It's nice to be able to download your waypoints to a topo map on your computer. You can also upload points to your 60csx, from your computer topo map, that you want to explore.
It's also easy to copy all the data form one garmin gps to another.
You can buy Topo U.S. for about $50.00