GPSbabel+ is great btw, thank you robertlipe
Now I have all the software I need for happy Geocache adventures with OSX & a Garmin 60CSx:
GPSBabel+ (to give .LOC friendly names instead of 'GC58E4'
Load my tracks (To convert .LOC files and send to Garmin 60CSx, then convert .LOC files to KML)
GoogleEarth (Import newly converted .KML files to display & keep track of Geocaches)
Now I only have to use Windows to load Garmin TOPO maps from the Mapsource CD, no worries