I also use a Garmin GPSmap 76 (although not the color version). As ishoot308 has done, I've mapped the trails I ride, and marked waypoints at junctions. I use the ExpertGPS program ($50 bucks and well worth it) to download the route and display it on a topo map or even Google Earth. I've attached a sample. The track list that is exported is in XML format and can be easily shared with other Garmins and converted to other formats.
Even before doing the mapping, its useful in knowing where you are when on new trails. For example, this past weekend, we were on the trail from mid-way up the Sandwich Notch trail down to Little Squam for the first time. Beautiful trail, but hard to know how soon we'd be having lunch at Walter's Basin. With the GPS, we could see our progress as we got closer to the lake. We also could match up the position from the GPS against the trail on the M'boro snomobile club map.
By the way - don't plan on taking Red Hill road from Bean Rd. Its being plowed this year and commits you to over a mile of mud. No GPS will tell you that.
The GPSmap 76 can be uploaded with the local roads, although they aren't all named. I've started taking my car GPS, a Nuvi 150, along as well. It doesn't handle off-road well, but is much easier to see while riding. It also has all the roads well labeled. I don't go out without at least one GPS, and look forward to having it guide me home today when I venture out on the lake in the snow storm.