I use this really basic software to back up my Etrex data http://www.easygps.com/
Might be worth a look. There is also the Garmin Mapsource software, it may have even come with the new gps, otherwise you have to buy it.
I made up a cable for it myself, but you can find them on ebay at a reasonable price. Cheaper if you have an old computer with a com port as you don't need a usb converter.