All drivel. Windows succeeds because IBM chose them as the OS of choice in 1981. Since then, they have been a monopoly. Windows 7 succeeds because it extends a monopoly. Vista was 'successful' by those standards. You just don't know better, but Windows blows. It's slow, takes huge amounts of memory, and is a sad joke to real operating systems like z/OS or HP/UX, or other real ones.
XBox 360 isn't particularly successful, but I did give them credit for at least being competitive. But, if you compare sales with the Wii over the lifetime of the machines, it's poor. It's right there with the PS/3, so not pathetic by any means, but still not overly successful.
How about all their failures? They've failed in tablets. How about that Zune? Nice, huh? How about their thus great success in smart phones? Yes, and their tablet software has done what? How about Mobile 6.5? Great effort there. Oh, and how is IE doing since they haven't been the only game in town? Oh, yes, they're doing great? Come to think of it, how has Bing been doing since their great launch? Hmmmm, not so great? MSN has done well as a portal sight? Hmmm, maybe not. How did they do as an ISP anyway? Yup, another failure. The list goes on and on. Even Jobs said they are irrelevant. They are.
So, really, where are they successful? Operating Systems was given to them by IBM. They illegally created a monopoly in the Office space because their competitors had no OS to leverage. They illegally gained a monopoly in the browser market, which the market is correcting slowly but surely. XBox 360 is their greatest success, and isn't really much of a success, being second out of three, and much closer to three than one in terms of the lifetime sales of the unit. Every place else, they've failed miserably.
All three of their monopolies are being eroded. They aren't even a monopoly in browsers anymore, but the sick man in the group, being consumed by competitors like a wildebeest beset by hyenas, lions, leopards, and ugly baboons.
How about the one area you point to as so successful, and their strongest position? Oooops, they've been losing market share to Apple for years now. Oh, and they already lost the war for servers to Linux!
Office? They're losing share there as well, although not too quickly.
Their offensives have failed, they can't gain any traction in a market they can't leverage a monopoly in. Their monopolies are weakening, with new markets (like tablets) they couldn't create, and their own markets slowly eroding.
Microsoft used to pretty much own the software industry, and got away with murder because they called all the shots. It's just not so anymore. Their arrogance, and incompetence has hurt them, and they're less important than a number of companies now.
That's not success. It's not pure failure since they're profitable, but that's based on a monopoly, not creating or being successful in new markets.