A
pejorative reworking of
Windows, the flagship operating system of software company
Microsoft. The same sort of people who use "Winblows" are likely to refer to Microsoft as "
M$" or "
Micro$oft."
Let's face it: contrary to what the person referring to "M$ Winblows" thinks, none of this is especially clever - it's obvious and unoriginal and juvenile. Often, it identifies the speaker as a Linux user, and one that fancies themself a rebel and an outsider, standing up to the Man by asserting that Windows blows (it doesn't, as of Windows 2000, really), and that Microsoft is out to make money (they are, to a fault). (NOTE: This is not to say that this description applies to all Linux users; it doesn't. Only to the stupid ones.)
I recommend tuning out anyone who uses Winblows, M$, or Micro$oft in an unironic manner. It's likely that they're another zealot to be thrown on the pile, and probably aren't worth listening to.