does the engine support d3d ? , in windows it becomes the ideal choice
No, there is no Direct3D support.
Personally, I don't believe D3D is the "ideal choice"... OpenGL works quite great (on Windows too). OpenGL/OpenGLES is also the only choice for 3D outside Windows: think Linux, Mac OS X, Android, iOS... It has a clean API, and, to the best of my knowledge, modern OpenGL versions offer the same features as latest D3D versions.
Of course, it is possible to implement D3D renderer for Castle Game Engine --- contributions are welcome

I just don't see a need for it, in practice. OpenGL rocks (on Windows too) in my experience
