3-2/50 means you have version 5.0, and you have the 'mono' nav. The nav unit is integrated into the radio: this is kown as radio-nav, or 'mono' nav, as it does not have the full colour map.
(correct me if you have a different nav unit!)

The newest software will provide bug fixes and improved functionality and is worthwhile. You need to download a nav OS version - any OS disc above v24 will do - and burn a CD.
The OS-disc contains different versions for different nav systems (eg: Mk2, Mk3, Mk4), that's why the OS-disc version is not the same as the nav version.

NOTE: the OS CD must be burnt as Mode2/Form1 format, if you use ImgBurn it will make the right format OS CD.
Make sure you verify the burn afterwards.

Then turn ignition to Pos1, insert the OS CD into the nav and follow the onscreen instructions.