(V): There is no DX11 for XP and i suppose Microsoft do not have plans to develop it in the future either. They have not made dx10 either for xp. There are some third party hacks for dx10 in xp, but i'm not very convinced about them. Maybe there will be third party versions of dx11 for xp but i wouldn't hold my breath.

As far as Linux goes, even older versions of dx do not run perfectly under Wine. Proper dx11 support might come some day but once again, do not hold your breath. OpenGL is the graphics standard in Linuxes anyway (of course DX includes more than just graphics).

So i guess only way to properly run dx11 software is to get Windows 7.