At work, I use Windows 7 like most of the rest of the world. Win 7 isn't half bad, to be fair. There are things for which I do need some kind of a Linux environment and for those I generally use Cygwin or, increasingly, Debian with LXDE in a VM.

At home, I hardly ever get to use a big computer. So my choice of an OS oscillates between Maemo (99%) and Sailfish (1%). On the rare occasions that I do get the chance to fire up my laptop, I use Windows 8 it came with. I hate it to bits but I use it too rarely to justify doing something about it. I only use it when I absolutely have to, like to book a holiday (those websites are too heavy for the poor N900).