Newton game dynamics is a very cool physics sdk
in my oppinion , but hard to get everything wrapped for easy coding if your planning to do it yoyrself , i did my own newton implimentation along with scythe physics editor way back
into the irrlicht engine , i loved the physics and all
the possibilities it overed but when it comes to
time and eas of coding i guess physx is better as mentioned
Unless there is an existing wrapper wich offers
ease of use also