Well, we finally bought a GPSr for Geocaching this afternoon at LLBean. We picked up a Garmin GPSMAP 76. (Please don't tell me it's a bad model...hmmm...it IS a good one, right? ) It has a "12 channel GPS receiver with WAAS" and "it's waterproof and floats". So, what's MapSource and do I need it? The guy at LLBean couldn't tell me.