PhysX is hardware accelerated on NVidia cards (GTX 400 series and above only I think) but not AMD cards, otherwise its a fully functioning high quality physics library that you should seriously consider (assuming the license is compatible with your project, dependant on what the project is you may have to pay or you may be able to use it for free). It has been used in many commercial games: Mirrors edge, arma 3 (when released), mafia 2, metro 2033, ghost recon, borderlands 2, batman arkham asylum (and city) and quite a few more.
Havok is a commonly used engine in the games industry although its not free to use unfortuneately. There are too many games to list that use it (326 here: http://www.giantbomb...s/92-502/games/
). EDIT: It is apparently free for some projects although I can't find anything on the havok site with any sort of guidelines or even priceplans.
Newton is apparently a bit more limited, true if you want to roll a ball down a hill then its overkill but I wouldn't make a serious game with it. Infact the only game I've actually heard of on their list of games using it is ship simulator which is something that has a billion copies sitting on the bargain rack of my nearest PC game store.
Bullet is a pretty good engine. Although by default it runs on the CPU like most engines they do now provide libraries allowing it to use CUDA (Same thing that PhysX uses for hardware acceleration) aswell as OpenCL (which can optionally be hardware accelerated on most GPU's). It has been used in GTA4 and red dead redemption aswell as a few open source projects and movies.
With the exception of Havok they all have publically available bindings to be used in several languages so whatever language you program in one of the above should be available to you.
Personally I would look into either Bullet or PhysX
Edited by 6677, 05 August 2012 - 02:08 PM.