Depending on where you chose to install your direct X 9.0c you may have accepted the default so look in here...
C:\Program Files\Microsoft DirectX SDK (August 2007)\Include
...and you will see a hole slew of .h files which are obviously header files used in the include area of your development that requires direct X files.
And then here is the path to where you may need to get the required files for DirectX9.0c to add to your friends computer...
C:\Program Files\Microsoft DirectX SDK (August 2007)\Redist
This is as far as I have time for as we are all working no stop over and over and over to get our 3D games going. Time.....
Maybe more experts who know more thn I do could jump in here and help out some more.
jjsjr
You know for a fact that you have reached the edge when you can absolutely see sound!