Are there any mapping programs for Linux?  

I found http://www.gnomad-mapping.com, but they don't seem to have anything
I can download yet.  I just want something I can hook my Garmin GPS up to,
and have it display a continuously updating map with my position on it.
Even better, if I could upload maps using it then I wouldn't have to use
Garmin's windows software.  WINE chokes on anything related to a serial
port.

Jay