Greetings!
PRE-Flight ver 1.9 (just out) now supports the Microsoft .x 3D file format. FMS model makers can now port their .x (and .bmp) files into PRE-Flight (using AeroDesigner) and take advantage of PRE-Flight's physics and model animation capability (like moveable control surfaces, propeller animation, etc.). See:
For free download.
Enjoy!
Regards,
Jose