Wrong, Windows has three version. XP, Vista, and 7. Unless, of course, you are writing server software which in this context you clearly aren't. Granted it may be possible for an insane nutjob to develop against five different versions of the MS redistributable C++ library, but only an insane nutjob would do that.No, windows has much more versions, but they happen to break when running pre-pre-version and happen to need 9000 versions of older libraries, incl. bugs, incl. building functionality based on erratic behavior.