I got the Garmin GPSmap 76CSx a couple weeks ago - and I love it! I just started geocaching, but have used the gps in the car, on my 4-wheeler, and it's phenomenal. I got this one because it has improved reception in deep woods and ravines, and it's waterproof.
After a 2-day ATV trip in West Virginia, I was impressed. It never lost signal, no matter where we went. When I rolled my ATV into a mud bog, I broke the handlebar mount but the GPS is still going strong. The gps has been dead-on with the caches I've found so far. In fact, I'm probably going to buy another one for my boyfriend - so he can have one in his truck, and he doesn't need to 'borrow' mine!