CUDA with D3D9 and C++


I just tried to add cuda into my D3D engine, after I simply added 

#include <cuda_d3d9_interop.h>
in my D3DEngine.cpp some errors appeared like
cuda_d3d9_interop.h(66) : error C2143: syntax error : missing ‘;’ before ‘__stdcall’

And this problem is similar to that when you modify the CUDA SDK project like to simpleD3D.cpp

Any idea? Or should I just put my main D3D application in .cu format?

BTW, once the .cu files loaded in VC++ 2005, it appears to be all black and white like text file.
I just want to edit it like in .cpp mode, having comments like green and keywords like blue.
I tried this by add *.cu to Tools->Option->Project and Solutions->VC++ project settings->C/C++ file extensions

But no change took place. How can I solve this?

Check out the D3D9 interop samples in the CUDA SDK.