The power of this Ageia PhysX card is impressive... but like the others said... it's limited to very few games... as the name says it's only for physics in games and it can handle a lot of objects at a time... and most impressive the ability to calculate fluids in real time... but at the moment it is not worth, because there are too few games to play with it...
But if you want to take a look you can watch some videos at their homepage:
http://www.ageia.com/physx/videos.html