Here's the "official" deal.

Yes the game requires DX9.0c to be installed. It also requires a game that supports shader model 2.0 in hardware.

No 2.0...no run. It's as simple as that.

With that being said, ATI cards run the game just fine. ATI drivers do have some issues supporting certain components of DX9.0. While that is technically "their" problem...it's really "our" problem as developers. The burden is on us to find work arounds for those features that are not supported on ANY card...even when they are technically "supposed" to be.

With THAT being said, at the moment the game looks identical on all hardware that we run on and that includes various ATI Radeon cards (mostly 9800s and some X800s) and a variety of NVidia cards (5900s up to 7800s).

However, performance is another issue. While you can technically run the game with all of the optional graphics features turned on and maxed out, on some of the lower end 2.0 cards (9800s, 5900s) performance will degrade...as expected. But that's why they are "options".

So, for all the ATI peeps out there, rest assured that the game will run just fine on those cards.