Hi Ian,
I am not from Laminar Research; just a flight simmer.
Is your installation a "complete" package?. What I mean is, are all of the X-Plane files in the one directory and not mixed into other directories on your "C" drive?
If it is "complete" in the one directory, the process is "extremely simple". All you need to do is perform a normal windows style "cut" from the "c" drive and "paste" to your new location. This is one of the benefits of X-Plane whereas other flight sim packages mix files all over the place.
If you have a desktop icon you will need change the properties to the new location or create a new icon.
Good luck with the transfer.
Glenn