How big of a problem is this? Sounds massive...

Nvidia Reportedly Limits PhysX Support to Nvidia-Only Graphics Sub-Systems.
Nvidia Disables PhysX for Systems Containing ATI Radeon in Addition to GeForce Graphics Adapter

Full article here:
http://www.xbitlabs.com/news/video/display/20090929095918_Nvidia_Reportedly_Limits_PhysX_Support_to_Nvidia_Only_Graphics_Sub_Systems.html

Sorry if this is a duplicate, I didn't see it when I quickly browsed for it.

I would imagine it would affect a few (Those who have both Nvidia and ATI cards in their computer). As I can understand the article; it just disables hardware based Scenes if you have an ATI card in your computer. Which is normal anyway, ATI cards can't do CUDA as it's a NVIDIA only implementation.

You still have the processor to simulate the scene - which in some advantages can be multi-core which you can split up the Scene threads between them, and I've only seen hardware scenes used for gimmicky effects; cloth and fluids.

But if anyone has an ATI card and PhysX Installed, download the attached zip and do:

flour --cupcake cone.nxs

Tell me what happens.

Hello,
ATI Radeon HD 3200, PhysX System Software 9.09.0814
It works fine.