Since I saw several, "this is broke threads," I thought I might add one with the steps I took on Win7/64 that made it work.
This is how I did it. You may be able to change the order.
1)Install and Activate your DBPro
2)Install and Activate Dark Physics
3)Follow the read Me in the DarkPhysics_Update_105.zip
a) Update DBPro (7.2 was what was available)
b) Install the PhysX Divers from NVidia's Website
There maybe a newer verison when you read this, but this worked for me. http://www.nvidia.com/object/physx-9.13.0725-driver.htm
c) Update Dark Physics
4) Reboot (this may be optional, I did it for good measure)
After that I was fine to run/build demos. Note that the actual instructions take you to a developer sign up page. I don't think I will have problems when making project based on other comments. But if I do, I know where I go off-course.
Get Music stuffs here http://soundcloud.com/seraphicpanoply