3d Ball on a curved path

Hi, I am a noobie to Unity. I would like a 3D ball object to follow a curved path. I was thinking of using the RigidBody API but I am unable to get it straight. Is there any way to do this using a built-in function call? Do I have to track the position of the ball all the time and apply torque ( as I understood from some other posts, though not clearly).

I really appreciate any help in this matter.

Thanks, Vivek.

I think that this will help you:

http://www.unifycommunity.com/wiki/index.php?title=Spline_Controller

you should take a look for iTween library.

http://itween.pixelplacement.com/index.php

its free and it can do such thing.