Global Positioning Systems
http://www.globalpositioningsystems.co.uk/
OziExplorer
http://www.oziexplorer.com/
Tracklogs
http://www.tracklogs.co.uk/cgi-bin/publ/user.cgi?obj=home
Easy GPS
http://easygps.com
Expert GPS
http://expertgps.com
GPS Trackmaker
http://www.gpstm.com/
The GPS can only store limited amount of information, say 500 waypoints, maybe 20 reversable routes and perhaps 10 tracks, so at some point it is going to get full and to add new information you would need to delete some of the information you have put in already , ie delete routes you have spent precious time creating. So instead of losing them, you can save your tracks, waypoints, routes on your PC and then delete them from your GPS to make way for more