I would not compare NVidia 200series with ATI 5000series cause it's stupid to do so. 200 series are DX10 and 5000 series DX11 cards. Speaking of DX10 and DX11, the current state of the market says that we don't need it. All games are still on DX9, pretty much. Maybe the reason behind it are Consoles and considering the fact that Sony and Microsoft wont replace their Consoles by year 2014 tells me enough. We ain't going to see fully utilized DX11 by year 2013, speaking of which i don't think Microsoft will push any new DirectX with Windows 8.
I am glad Doom 4 is going to be using OpenGL, it's time we revisit OpenGL again
. If you already bought Crossfire ATI setup with 5000 series and even though Fermi is going to be faster then ATI counterpart, it's not worth replacing it. SSD Drives, USB3.0, SATA 6, 6 Core CPU, a bigger Monitor sounds a better deal.