How to enable hardware PhysX processing?

[Enterprise2448]

After running the techdemo at about 22 fps and the game itself at merely 12 or so, I came wondering if the PhysX work is being done by my CPU or GPU. Where can I set it to be done with GPU? I am using 8800GT, afaik it is PhysX capable.

Great game btw. Superb infact, can't wait for english release. Although I am having trouble running the game with SM 2.0 or 3.0, the textures are just missing everywhere.