The GO is pretty much designed to stand on it's own, no computer required, unless you want to hack it.
It is possible to send waypoints, like Geocache locations, to the unit, but from what I hear it is somewhat difficult on a PC, I have no clue about Mac's. The cable cost more than half of the units price, and the alternative is making a cable, which is not particularly hard but tedious. The programming end sending NMEA sentances is where I get lost.
Basically I would be leery of the GO. While it has some definate advantages (Price, basemap, nice antenna for GPS) it has drawbacks when it comes to Geocaching in that there is no easy and direct way to interface with a computer.
Thanks so much for the info. We were seeking the least expensive model since we're just starting. So I've been trying to research this using your forums. If we want to download the waypoints of our Mac would you recommend a Garmin. Many people have been mentioning Etrex or Legend. How do I find out if I can use my eMac? It does have a USB port.
Thanks.