On our trips around the South West of the US we use 'moving maps' for navigation. There are several software packages out there that use topographic maps in conjunction with live GPS data to display the current position. The program I have chosen is OziExplorer. This program was developed in Australia by Des Newman. It is designed to operate with scanned map files and has useful features for trip planning as well as real-time navigation and record-keeping during a trip.
A number of 3rd party utilities and add-ons are available. Dave Patton maintains a good list of them on his website.
Since the program comes without maps it takes a little time for a new user to get his first moving map on the screen. It appears that this is also the reason why some people never get much past installing the trial version. Since I set up some friends with maps I decided to go one step further and clean up my map collections for the South West of the US and make it available on DVD's to interested parties.
Here in the US we are in the fortunate position that we can get all the scanned topographic maps we need from the USGS. There are various download sites that provide data for individual states.