I use Route 66 USA on a Powerbook G4 and my wife uses it on an iBook G4. Both are running Mac OS X 10.3.7. It works great for both of us. I have not had any problems with it at all. Both of us use Globalsat Bluetooth GPS receivers. I travel extensively throughout the United States and it has been fairly accurate. She has traveled in Canada and found it accurate there. Sometimes when searching for hotels it does show them in a different location than they actually are but it also provides a phone number so you can call on the cell phone and while looking at your map figure out how to get to the hotel. It is not as good a Street Atlas for Windows, but it is all there is for Macs running OS X. Maybe they will develop an upgrade soon, but so far all queries to them indicate nothing new.