I have been running MSFS since FS3 was a wiring diagram. I have had FS9 as my favorite Flight Simulator since it came out. I have tons of Scenery and (literally) hundreds of aircraft in this program, so I am content to keep running it till it (literally) crashes. As a result I have little regard for FSX, although I would use it if FS9 ever gave up the ghost. I put FS9 and all its add-ons on a dedicated external HDD so that it will remain uncorrupted. I switch this external drive between my many computers as needed.
Recently I acquired the latest version of a gaming PC and I have uploaded the basic FS9 program because this computer has a smoking fast processor and tons of RAM, and a super-fast graphics card with water cooling. It also has a three-screen cockpit setup, and I constructed a simulated cockpit enclosure to make simulated flying more enjoyable. I'm trying to transfer my scenery and aircraft files from my old external HDD to the new PC, but I keep running into errors. The files transferred into the wrong destinations, I guess, although I specified actions so they would end up in files corresponding to those in the old program. At any rate, even though some of them wound up in the same destination files (:/FS9/aircraft and :/FS9/scenery/addonscenery) the program refuses to recognize them.
Thus my problem: What is the secret of the transfer process so that files easily recognized under the original FS9 program on the HDD will also be recognized under the new gaming PC FS9 program? I look forward to an answer from someone. Please be very basic in your answer and pretend I don't know much if anything about the process.