Hi there,
So for the OBD2 scanner you will have to double check if it works on JDms im not sure, i know in Europe there was some regulation passed years ago that meant cars had to be compliant with obd scanners.
As for your current sat nav i personally would throw it and sell it on ebay, a car pc is much more powerful, play movies, music, satnav, car engine specs and read out (assuming the obd2 works), view the web, work and wordprocess all in your car!
If you just want the PC and not the cubby (as you already have yours) then do pm me for more details!
thanks