You can download free topographic maps from here, and then use Garmin's software to send it to your GPS. There's a few steps involved, but I can't remember them off the top of my head.
http://www.gpsfiledepot.com/As far as seeing the actual trails on your map: I don't know what the "best" method is, But I tend to download other people's GPS tracks and then send them to my handheld GPS. The downsides:
- Tracks might not be 100% accurate - but I honestly haven't had any real problems.
- Handhelds are limited in the number of tracks they can store. I think mine can store 20 tracks.
I have a lot of stuff from Sipsey and Cheaha. Send me an email and I'll gladly share my stuff.
globetruck@gmail.com