Cees, just to give you a little more information about what happened:
In SP2, the way the textures are shown is different from before. The Alpha Channel of the texture, which defines its transparency, is inverted.
In FS9, FSX, and FSX SP1, a white Alpha Channel means a transparent texture, and black means opaque.
In FSX SP2, white means opaque and black means transparent !
This is why your plane looks transparent, it was made for FSX SP2, so your FSX was not handling its textures correctly.
This is also why many FS9 planes will have opaque canopies. Of course this problem can be solved easilly most of the time, by editing the alpha channel of a texture with DXTBMP, a freeware texture editor.
EDIT: Oh ! And welcome to the FSX world
