I think that will work. The requirements are an 8 series or newer card because the PhysX is handled via CUDA code so you need the unified shader architecture. The 7 series and below has the pixel and vertex shaders separate. The card also needs to have 256MBs or more of memory. The prevents any "turbo cache" cards from being used.
There are a host of reasons why this is a bad idea however. First, that card is a lowend card so its ability to run CUDA will be horrible. As in if you bought a GTX560(TI) and ran the PhysX on it you'd get better effects. Second, Nvidia prevents what you want to do when it detects an AMD card being used. There are hacks and tricks to get around this, but why bother? Third, few games support running PhysX on the card. This means you are probably better off spending that $71 on a faster CPU, or an SSD, etc. Something that will matter in more games/things.