To install FS2004 (FS9) aircraft into FSX:
FS2004 (FS9) aircraft do not port terribly well into FSX. The principle issues are slower framerates and problems with transparent parts (eg. prop disk and canopy). However, if your computer is sufficiently powerful and you don't mind the compromise in appearance, then the aircraft are fully useable. Note: They will work much better in FSX without SP2 or
1. Using the downloaded aircraft installer that came with your purchase, install the files into a folder of your choice.
2. Place the individual aircraft folders from the above folder into C:\Program Files\Microsoft Games\Microsoft Flight Simulator X\SimObjects\Airplanes