Go with DirectX 11 and beyond: when you will achieve a decent skill to product something, even in China targeting XP will be probably a wast of time. There are a lot of DX11 tutorials ("legacy" directx sdk, microsoft "modern" directx samples on msdn gallery, amd radeon sdk, nvidia "legacy" dx11 sdk, new nvidia dx11 sdk, intel samples, and many online basic tutorials and a decent number of books).
OpenGL 4x/ES? Yes, that's an alternative, multi-os, open&cool, you will be a Penguins' saviour and Stallman&co will be happy... But first you have to consider some issue that happen/apply on/to OpenGL development (and not to DirectX development):
- Driver status: http://richg42.blogspot.it/2014/05/the-truth-on-opengl-driver-quality.html
- Differences between theory and practice: http://richg42.blogspot.it/2014/05/things-that-drive-me-nuts-about-opengl.html
You should also consider to use some high-level wrapper API like SDL: it will contains some of the OpenGL development headaches.
Edited by Alessio1989, 14 May 2014 - 09:00 AM.