I have been playing MW for a few years now on the Xbox, however I have recently accuired MW(with both Tribunal and Bloodmoon) over Steam(also using vista). I thought I would change it up a tad with the psychodog's better bodies mod. I have tried with the installer and manually but both to the same result. After I check the BB mod in the Data Files after startup and start a new game or load a save file I get the same message: Model load error: Meshes\bb\bb_skinm_de.nif
cannot load file in meshes\bb\bb_skinm_de.nif.
Will use the default object Marker_Error.NIF.
Continue running executable?
If I select yes, the game loads and everyone is surroundid by largy yellow polygons and the body meshes do not change to the BB meshes. If I select no, then the game shuts down.
Please, if anyone can help me it would be greatly appreaciated.

Redate the BSA files back to 2002 or even earlier. You can find free redate tools online, Nanotech date edit (I think) is oft-quoted.