Thanks for your advice, it worked.
I found the file called playlistx.jmd. I imported them into JRiver app like this and for the benefit of others here is how I did that;
FILE, select ‘LIBARRY’ from the drop down menu, then ‘RESTORE LIBRARY’. When the box appears in the middle of the screen press BROWSE. Find the folder location where the .jmd playlist or better still the whole ‘MC Library back’ up is located. Check both options boxes are ticked, finally select and press OK
The application will then restart.
What I found when I selected one of my old playlists was that the application was possibly a bit confused with the four hard drives I have in my desktop at present. Despite going into the options menu and telling JR where the music files where located it did not seem to remember.
Copied the latest MC Library back up file on to a USB stick (200kb)
I followed the same process above with my dedicated audio pc and it worked perfectly. All my settings and playlists restored. Great