errr I hope more than that are 3D enabled... all there is to it is tweaking the details and textures so that the game can render more FPS.... and since most HD games are PC releases too, there shouldn't be much problem for getting the materials.
for info, 99% of PC games are PC enabled.... they basically only need to not have the refresh rate fixed by the resolution (for example, KOTOR2 is not 3D enabled while HL2 games work just fine in 3D.)
Adding the 3DS in the equation sure helps understand the 50% by 2012 :p
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