I am also a newbie, with a similar question. So I thought I should gnome up this post rather than start another topic. It is completely unclear to me who if there is a clean leader in the software market. Its also unclear to me if there are other choices than a garmin GPS18 for a USB GPS. Garmin is possitively cryptic when asked about specs and path recomputation times, so I'm left asking the semi-pros.
-NP