There seems to be some scepticism about Microsoft's decision to roll out a full version of Windows instead of a cut-down version (or a sized-up version of Windows Phone 7) for tablet computers. Paul Thurrott has an interesting take on this, with MS trying to offer a familiar interface no matter what you're using Windows on. If Microsoft can pull it off and MinWin is somewhere near viable, they stand a good chance of making a comeback.
The simple reason is what everyone is talking about, apps. The App Store may be approaching 500k, but there are already millions of Windows applications and a massive developer base. True, they'll need to be ported to ARM for those tablets, but Intel is working hard to get a competitive processor into that market, so it may not be necessary for some tablets.
Then you could open and edit your Word documents, not in some cut-down alternative, but in Word. All those apps people (and businesses) are familiar with suddenly work on your tablet. No need to purchase a whole host again. In one fell swoop Microsoft would not just catch Apple in the tablet market, it would leave it in its wake, not to mention the likes of RIM, HP's WebOS and Android (which is trying so hard but making it so difficult for consumers).
That's before we get to their support for HTML5 apps, which again will be faster and easier to deploy, with a much bigger developer base than Object-C (used by Apple) and Java (used by Android). Microsoft appear to be solving the problem with competing with the App Store by going the route of overwhelming it. As we've seen before, walled gardens are open to attack. Apple doesn't care, it only needs a tiny fraction of the market to remain prosperous. They'll keep adding services to make money from those trapped on their platform and engage the rest on some level, but the fight for control of the consumer landscape will not be fought by them.
Let's not forget, Apple are small fry compared to Microsoft in terms of installed base (combined, iOS and OS X are a fraction of the 1.1+ billion Windows users), which means they have familiarity on their side. Microsoft may be down, but they're far from out.