If you don't use the UTM system on your GPS reciever, you have no idea how much more of a simple and effective system this is than the old lattitude/longitude method. This is especially the case with Topo maps, which have UTM coordinates printed right on them.

For what it is worth - there is a BIG movement in emergency services to standardize on the UTM system - it's officially called the US National Grid (USNG) and the "Datum" (sort of like survey data) to use is NAD83.

basically, with UTM, you have a simple "sector" like number and then two long numbers that give your position in meters within that sector. No "North Lattitude" no decimals, no minutes, no seconds - just a sector and a set of numbers that puts the crosshairs on your position on the map.

there's many great files on the internet on the subject.