GPU accelerated Physx is a worthwhile feature in approximately 5 games IMO. Of those the ones you would be most likely to play at this point are Batman:AA and Mafia 2. Perhaps use it as a Physx card and go through those games if you are interested in them but I wouldn't recommend using it long term as a Physx card. The 8800 Ultra used a lot of power even just at idle, over 70w. So outside of when you are playing the handful of games that can actually benefit from a Physx card it will just be sucking down power and raising your bill.