All of the planes on here will not work, why?
1) Some are made for FSX, some are made for FS9 (Century of Flight), and some are made for 2004.
2) You may not be extracting the files into the right folder: Computer (Insert Drive Letter here)> Program Files (choose 32 or 64 bit)> Microsoft Games> Microsoft Flight Simulator (insert version here)> Simobjects> Airplanes
3) Some files here are also textures or AI Aircraft only
...and some have been modified - "updated" by Mark Rooks...
Find a decent file library, there are plenty and read the file descriptions before you download a file and then the installation instructions which are usually included.