I have 2 genuine Windows 7 Pro x64 licenses, 1 genuine Windows 7 Ultimate x64 key, 1 genuine Windows 7 Home Premium x64 key, 3 genuine Windows 8.1 x64 Home keys, and a Windows Vista Ultimate x64 key. All of my keys are legit, and I paid full price for them.
I'm using a genuine version of Windows, it came already installed with my laptop, if I should decide to buy a computer I don't see why to spend 100$ on buying a license of Windows.