Article taken directly from 1up.com

Crackdown developer Realtime Worlds announced today that they're focusing the development of their massively multiplayer cops and robbers game APB on Nvidia hardware, whose PhysX technology is said to allow them unprecedented physics interactivity for a MMO.
Anyone who's been run down by phantom cars in Grand Theft Auto IV knows how hairy the physics can get in an online, open world action game -- let alone a massively multiplayer one. Realtime Worlds CEO Dave Jones provides a bit of reassurance, saying, "APB is a vastly ambitious project, combining the key elements of action gameplay in a living,breathing world with millions of players around the globe. In order to fully realize the vision of APB, it was essential to include next-generation physics in our game world. This is why we choose to standardize our development on GeForce GPUs and Nvidia PhysX technology, the combination of which has given our developers the power and freedom to deliver the first action and physics based combat gameplay into the massively multiplayer online space."

Apparently future drivers will allow users to use an Nvidia videocard as a dedicated PhysX card.  I think my 8800GTX should do the trick.