It doesn't matter if it takes load off the video card. It's still not worth the extra $140-200, to gain 10 fps...or a little extra eye candy. The 8800 series can handle all that, on it's own.
i think ur missing the point of the PhysX b1gapl. The PhysX titles that ONLY support the PhysX card will NOT support future graphics cards, persay the 8800 GTX or 9800 GTX. It's part of the coding that only allows the PhysX card to be used.
if i were to get some games that support the PhysX card, eventually i would get the card just for those games, because they dont support any other physics, just the card. Sure it seems like a waste of money, but $140 sounds cheap to me, but of course i have no job n no computer to run games or cards on....yet.
games that support the PhysX card r exclusive to using it, not any other physics in future graphics cards, so of course its alright to get it, BUT only if the person has the money for it.