I have just gotten StreetAtlas 2003 plus and it is the best mapping software I have ever worked with. They finally came out with a program that fits my GTD methods!
It gives you the ability to create different "maps" that can be turned on and off on the same "map background" so that, for example, you can see all your work errands, and then also compare to your home errands
It will also allow you to import a database from a contact manager and look at all of the addresses on the map and then edit them as well
about 100% better than Streets and Trips and with the GPS reciever, it is the perfect solution
If you look into buying it, make sure you get the "plus" version