Before you begin jumping out of your seat from the sheer excitement thinking about how well your computer will run Mirror's Edge brings, please take note that the following requirements for the PC version are the minimum system specs.
Alright? Now commence jumping!
In case someone had told you otherwise, the answer is no -- PhysX won't be required; it's completely optional. It's also worth mentioning that the supposed level editor for Mirror's Edge will not be making it in time for the game's January 13 launch date, if the toolkit ever gets released at all.
So, how blazing fast is Mirror's Edge going to run on your system?