Originally Posted by pioneerisloud
No you don't, since the 8400GS isn't capable of PhysX either.
The minimum requirement to support GPU-accelerated PhysX is a GeForce 8-series or later GPU with a minimum of 32 cores and a minimum of 256MB dedicated graphics memory. However, each PhysX application has its own GPU and memory recommendations. In general, 512MB of graphics memory is recommended unless you have a GPU that is dedicated to PhysX.
In other words at MINIMUM you need an 8600GTS / 9500GT or better. And even then, those aren't going to work well at all. It's usually more around 8800GT or better as a dedicated PhysX card.