OK, I have been keeping this under my hat for a while now. Maybe its now "old hat" by now. The name of the program is PATHAWAY.
It is a Palm application and it can be used with your gpsr either Garmin or Magellan. I was able to purchase connecting cables with no problem. Here is what I am doing for geocaching and professionally.

I am taking Delorme, Mapquest, Mapsonus, Yahoo, Terraserver etc maps and copying them to a file as a bitmap. I have also scanned my own hand drawn scaled map. The Delorme 3-D topo is the best. The application comes with a map converter for the desktop so you bring the bitmap in and convert it to a .prc file which also compresses it. When I hotsync it goes to the handheld. I bring the map up and go to the delorme software on the desktop and get two common point lat,longs and calibrate the map. You can also do this in the field. Go to two road intersections or identifiable points and store two points and then calibrate the map. The palm and gps work beautifully together. You can move points, routes, and tracks from one to the other with no problem. You can have several databases for the points. As soon as your map is calibrated, your already defined points pop up and you can navigate to them if you wish. I am using it professionally to inventory infrastructure. “Newspeak for sewers, water systems and storm sewers”. I am also using several other applications such as a projection program, mag deviations, cachmate, excel, word, etc and I can cut and paste comments, coordinates and whatevers between all. The nice news is the program has a 15 day trial period and cost about $50 if you like it. This thing does a lot more than I have mentioned such as bringing maps in as layers, but you can find all that out for yourselves if you are so inclined.
ng

Phooey ... another 'WinBlows only' desktop application ...

Looks like you will need to get an Intel based Mac. An AppleInsider article Speed of Apple Intel dev systems impress developers, says

quote:

"It's fast," said one developer source of Mac OS X running on Intel's Pentium processors. "Faster than [Mac OS X] on my Dual 2GHz Power Mac G5." In addition to booting Windows XP at blazing speeds, the included version of Mac OS X for Intel takes "as little as 10 seconds" to boot to the Desktop from when the Apple logo first displays on screen.