this may be a day late and a dollar short, but I use IMG2GPS tool. It's an automated loader that essentially does what MapSource does. I am in the same boat as you - just got my Garmin a month ago and I'm trying to master it, normally don't have a problem with such things, but I think this is the first tool I've bought that's smarter than I am.

I bought mine for use in IZ, I've been thinking about fooling around with GeoCaching, just to increase my familiarity with it.