This is not really fair, and I'm sure you realise that. As a random selection, and in roughly decreasing order of significance from "world defining" to "things you'd really miss if they weren't there":
We have a standardised desktop operating system that is familiar to nearly every computer user on the planet, with which an array of hardware more diverse than at any point in human history mostly just works, and on which software probably written before some people reading this were born still runs.
We have a history of programming languages that have advanced both the state of industrial practice and the state of the art in research, and both traditions continue to this day.
Until very recently, the majority of web pages were presented in one of a handful of carefully designed, screen-optimised fonts that brought digital typography far beyond its previous standard, which are available on almost all major platforms, not just Microsoft's.
We have a wealth of ideas regarding HCI, from more efficient user interface designs to accessibility techniques to support users with disabilities.
It's not difficult to think of more examples, and of course Microsoft have also participated in numerous collaborative endeavours over the years that have advanced the industry in other ways. No doubt an organisation with Microsoft's resources could have achieved much more in recent years with more visionary leadership, but the idea that their work has produced nothing more than a few hardware devices over the years is just silly.
And innovation in programming languages? I was using BASIC before Microsoft existed, and while I thought Visual Basic was a significant innovation, I knew the guy who actually invented it and know how Microsoft took it from him. ("Take our lowball offer or we 'invent it' ourselves and you get nothing.") Nothing Steve Jobs wouldn't stoop to, but not a great example of MS innovation.
And .Net was the MS response to the JVM and C# was their response to Java. Both were improvements, but it was obvious what they were improvements on. And those two (VB and C#) are the only MS languages to have any impact outside the research lab.
And fonts? Was it Bill Gates who took that famous calligraphy class and brought the world of fonts to "microcomputers", or was that Steve Jobs and the Mac? Was it Microsoft who joined with Adobe and created the desktop publishing revolution, or was that Apple, too? Well, yes, Bill and Steve did work together on font technologies later, but that was to try to break Adobe's font monopoly, wasn't it? That m-word again.
Again, I'm not questioning the idea that MS came up with many new ideas, and all innovations have predecessors. It's a question of degree: how big a change is this? MS's innovations, while real, were just not in the same league as innovations from Apple and Google, despite MS's enormous power, because MS's focus was on defending their existing monopoly from competition, while Apple and Google were more focused on attention-grabbing product innovation.
And then there's Windows 8.
Also, while we're on the subject, my 8 year old can put together an amazing Keynote presentation on an iPad. She has never used a Windows OS.
Find a modern 8-year old, who understand PC circuitry (at analog and digital level), seen manufacturing processes, can re-solder components, can write C/assembly, can develop basic useful applications (like, say MS Paint). I bet you could easily find one like that, back in 70s-90s, particularly here in the silicon valley. Now - I'm not so sure.
From "Basic -> C/assembly"? Wow. That escalated quickly.