I actually just picked that up the other day too. I had the same issue, and just re-installed the latest physx driver. I guess it installs an old (broken) physx driver during it's installation
and yeah, use dpfix. I knew I would need that before I copped, so I can't complain (thank you based durante). shyt's kinda cool because you can set arbitrary resolutions for the internal rendering and display, making it easy to downsample without changing the size of the UI. plus you can adjust settings that were never available ingame