The Garmin Etrex basic model is what we have - and we recently bought the Garmin E-trex legend which comes with a cable - It is a birthday present for my son who is moving up from cub scouts. ( I removed the cable and gave the GPS. This made the B-Day present more affordable since I was going to buy a cable anyway.) The cable works for both and makes it REALLY easy to put waypoints into your GPSr. You will need some software to do it - I use the GSAK software and really like it. At first I was not sure how to use it but soon figured it out. I really like it because you can sort your caches in any way you can think of, just about. You can hand enter each coord, but like others have told you, you "mark" a new way point, then edit it. The user manual does not really give clear instructions for entering waypoints for cahes. Good Luck! I hope my post helped.
