Just found out about hybrid physx about a week ago so though I'd try it out with me having a spare 9800GTX.
Hybrid physx (best thing I've heared of in tech lately ), only found out about it a week ago & was intrigued with me having a spare 9800gtx doing nothing, I'm on an oldish p45 motherboard also so didn't even think I could use 2 gpu's, using the latest ati & nvidia drivers but for nvidia drivers it needs patching in safe mode in windows 7, also need to setup a fake extended display in screen resolution too, but I'm buzzing now I have best of both worlds, tested it out on the Mafia II demo & can have physx on high with massively better fps , the only reason I want to get a gtx460 is so I can have all the apex cloth physx with good fps, I deleted all the apex physx cloth files except for main characters clothes, I'm sure that with a GTX460 I could keep all the apex physx coth on so thats my next pc upgrade .
Link to the source so glad I tried it .