Collision with diagonal surface

Ok, I'm having a bit of a problem with this.

A ball is dropping in free fall (not spinning/rotating or anything).
After a given time it collides with a diagonal surface (a total inelastic collision), it then begins to roll down from it.

How do I find the velocity that it begins to roll down the diagonal surface with? Do I just regard the ball's velocity as a vector and find the component that is parallel to the surface?

>>10
Oh I see.
So you're actually splitting the kinetic energy up, and letting the energy in the right angled direction getting destroyed.

Ok, thanks for the help.