It may run DX9, as DX9 is desigend to be backwards compatible with older VPU's, but its not a DirectX 9 graphics card, you will not be able to utilise some of the advanced features which DX9 features like the advanced pixel shader.
I'd deffinately recommend you get an ATI card, im not going back to nVidia now, i find ATI boards to be better in most ever way, even down to the website and drivers distribution, nVidia release new drivers almost on a weekly basis, most of which arent WHQL tested, ATI on the other hand release new Drivers in good time, and the actual drivers are ALWAYS WHQL tested and are always of high quality.