You should be able to restore whatever you need to from your install disks - rather than do a complete re-install.
Check out this marvelous resource:
http://www.cat-tamer.com/flightsim/faq001.htmlIt shows where everything is on your install disks and how extract just what you need.
I also recommend
fs9cddir.zip Compiled by
Brian Collins (not sure if it is in the library here but you can find it at Flightsim and Avsim for sure)
This is an Excel format listing of all the files on your install disks. A great resource to keep handy.
Good luck!