Just want to know what ratio of people run other than Windows on their machine (also it is very interesting to know what kind of Windows they run).
If you dual/tripple/multiple boot, choose the OS that is more important for you (for example I dual boot too, but use XP very occasionally (once a month) for gaming purposes, so my OS of choice is Linux, even my car runs Linux

Linux only got one choice because there are too many flavours which are not much different (unlike difference between XP and Vista). So is BSD.
EDIT: for some reason I had OTHERS section but it does not show, so please put down what you use if you use something else that is not on the list.