You do need to install the DirectX 9c from the game. All of the versions of DirectX after it leave out parts that the game requires to draw the "old" 3D stuff. Also, with Steam, do NOT install the Silent Hunter games in the C:\Program Files folders (which includes the x86 one on a 64-bit machine). Else, Windows will assume control of your game life, and will not allow you to apply mods. Use the Steam App on your computer to "Manage" the install, as per
Steam themselves. This info is also in THEBERBSTER's
SH4 <> TUTORIALS <> HOW TO DO IT <> INFO < thread.