Microsoft wins because the albatross of XP will be off their PR necks. Every unpatched security hole will still look bad, even if they gave people years of warning.
Users win because (hopefully) they are using a better OS.
Or they don't want to bother with buying new hardware. A friend of mine is still using her 10-year old laptop with 1GB memory and XP. And it works just fine for her purposes (web browsing, gmail, little office).
Excluding post-PC products, classic desktop and laptop OS market share is:
Windows - 90.8% OS X - 7.7% Linux - 1.5%
Linux has a long way to go.
Latest Linux gaming renaissance eats at their confidence. For many gamers Windows is not seen as a requirement anymore, and they simply ditch it and start using better systems (especially because Wine became so good lately). While gamers are a minority amongst Windows users, MS still fears that dynamic because it breaks their network effect and creates the same effect in the Linux world.