Free Maps!
No, not Google Maps.
In this case, it’s a free, trial version of MapPoint North America 2009 and a free, trial version of Streets and Trips 2009. Not sure how long they’ll be free, though. Also, not sure what GPS units, if any, these are compatible with, but it’s implied that MapPoint is with at least one, based on some of the information I’ve read.
So, quick, try them out while you still can!