I'm a GPS newbie, and I am lost. I recently acquired a Garmin GPSmap 478 along with a recent bike purchase. I do not yet know if it's for me or not, but I damn sure want to try.... It came with almost all the accessories and bits from the original purchase, except the Trip and Waypoint Manager software. I decided that I would update/upgrade to the Topo 24k maps thinking that I'd get the T&WM with it. The clerk sold me the 24k on SD card......not cd. The unit was registered with Garmin by the original owner. I have tried to register with Garmin, no go. I have tried to sync the unit with my computer, no go. I have now realized that the SD card version apparently does me no good. Due to the retail packaging, I "assumed" that I was getting a cd, but I did not. Must I have T&WM on my computer in order to communicate with the unit? Will Mapsource load from the SD card onto my Laptop? And then will the maps upload to the unit from the Laptop? I'm a frustrated and challenged (read embarrassed) newbie. Any guidance appreciated.