always open gl could not be loaded! WHY???

I want to play Star Wars Jedi Knight II! It begins to start, but the popup always says "could not load open gl subsystem!
I dont see the reason!
Please help me!! :-(((

Have you got a 3DCard with the apropiate drivers?
Have you got the right version of Directx?
Have you the opengl32.dll in your winxx\system?
etc, etc…