My appologies if I am repeating what has already been said on this forum, but I have been absent from the forum for some time.
With respect to electronic maps I would observe that programs like Streets and Trips are great for short courses, but if you try to get a map covering 10km or more you need to zoom out too far and loose the detail. It is possible to set your screen at a high resolution and then electronically shrink the map or combine several images, but it becomes increasingly difficult to read as the scale goes up. It is a good idea for some routes, but for others a custom map is still the best thing to fit on a single letter size page.
Microsoft Streets and Trips is a great mapping tools as Kevin points out. Just as good, and free, is Google Map at: http://maps.google.ca/ which even allows you to view a satellite image or combination of map and satellite. An enhancement to the Google Map is at http://www.sueandpaul.com/gmapPedometer/ that allows you to measure a route and event charts the splits for you. Google also has a very neat satellite application called Google Earth at http://earth.google.com/ (the basic version is free and the GPS enabled version is only $20US). The new version (still in beta) of Garmin's Mapsource integrates with Google Earth. The Google Earth image is very detailed and you can even measure the SPR by measuring a track from inside corner to inside corner. I have used Google Earth to lay out a complex 15km route and was with 20m. Tomorrow I measure a 10km route and will see if I can repeat that accuracy.