opinion needed, Collision detection and response

Just get started on this program where I need to develop a CD related software.

I am familiar with OpenGL and only started to discover bout OpenInventor. I heard Open Inventor does make your life easier but I just feel uncomfortable with it. Is it common to other (where u can handle OpenGL but do not have a clue at all with Open Inventor?) And I am new in CD and want to ask you veteran programmer that should I started my coding by using OpenGL as API or just OpenInventor should enough to handle. In my opinion, I guesss OpenGL should survive even for some advanced CD while OpenInventor cant capable to handle that. Correct me if I was wrong. Thanks.

Please feel free to drop a msg(even it is only a line) and I really appreciate all kind of opinions.