Saw this on another and it works.

Navigon US maps :

1.Download hxxp://navigon.vo.llnwd.net/o25/u/us/update/1.2/win/NAVIGON_7100_Updater_Version_1.2.exe
2.Install on empty SD card or USB stick, min 2GB
3.Copy *.map files from there to your phone SD:/Navigon/maps
4.Enjoy !!!