I'd recommend to export and import only the HKEY_CURRENT_USER\Software\JRiver\Media Center 14 registry key.
HKEY_Local_Machine... is mostly machine and OS instance specific and it does not store user settings. It may cause problems if it is restored from a different OS instance.
EDIT
I'd do the following:
1) Verify that the media files are in the correct locations (as they were before). If a separate cover art folder was used replicate also that folder.
2) Install MC and the plugins, skins, etc you want to use.
3) Restore the library from a library backup file. (...or each library separately using an individual library location if you have more than one library. You must back up each library to a separate backup file.)
4) Import the exported registry data to Windows registry. After you have done this, check that the restored library is (or libraries are) still intact. Do the step 3 again if you find anything that is not correct.
EDIT 2
If you are not familiar with exporting and importing Windows Registry items make a Google search and educate yourself first.
If that seems too much trouble you can always do it in the old-fashioned way:
Have a piece of paper and pen ready, browse through the options and make notes of your favorite settings.