Whats a good physics engine for 3dgs version A7.

If you know a good one could you also please post a little tutorial on how to use it. I will be grateful.
Many thanks to the people that help.

What do you want to simulate?
If you have no special needs, the built-in-physics-engine (ODE) is okay and easy to use. You can also have a look at newton, there is a wrapper developed by Vet.

Sorry not A7, A6 with lite-c. Soon ill have A7 im gonna buy the 100$ version