I know a guy, reasonably sane and responsible in other contexts, who bought Dell shares about a decade ago and promptly forced his entire company to abandon Apple in favor of Windows 98 on Dell - thus starting them down the path to Wintel churn they're still on despite having "let him go" for unrelated reasons a few years after the Windows 2000 changeover.
What he recognized, and most others don't seem to think about, is that the admirable market success earned by companies like Intel, Microsoft, Dell, and HP comes at a price to the customer - every dollar a company like Microsoft, Intel, or Dell makes is a dollar some customer gives up.
If the customer gets fair value for that dollar, then great; that's how capitalism is supposed to work - so the question really is whether his employer ever got value for money.
To understand why I doubt that, you need to understand why I, and others like me, object to Windows purchase decisions. We're not anti-Microsoft and we're not anti-Windows: we look and sound that way because what we are is for Unix.
Thus when I looked at the Windows 7 beta recently I thought it a lot better than Vista, and so my standing recommendation for Vista users now is that they upgrade as soon as they can - I'm not, in other words, arguing that Microsoft hasn't come a long way since QDOS.
Unlike a lot of Microsoft "fanboys", however, I'm also familiar with the MacOS X Unix desktop, the Linux environment, and the next generation Unix ideas being brought into the market through Solaris. Compared to earlier Windows branded products, Windows 7 looks quite good; compared to Unix, however, it's just not in the game: kludge piled on kludge, designed in scalability limits, single architecture, closed source, and a GUI that forces server usage down to a 1970s sh like command line and is five to ten years behind everyone else for desktop use.
But when I say stuff like this, people always jump down my throat with this business of Microsoft's OSes being the only ones to cater to the masses - making it the branding that has earned its near monopoly market share. It sounds like a winning argument, but the underlying premise isn't true: Microsoft doesn't cater to the masses, and didn't "earn" its market share by doing so. Microsoft and Intel cater to people who make money selling their products - and the reason everybody buys these products isn't that they're the best or the cheapest, it's that these are what lots of other people are motivated to sell.
And there's the contrast: I know people who sell Sun or Apple because they think these product sets are great - but the Wintel sales people I know are in it for the money. In fact, I think it's pretty clear that if joe high school could make as much money selling Linux or a BSD as he can selling Windows, Microsoft would have long since either switched to Unix or gone out of business.
So really why did my friend switch his company to Dell? because he thought it would make money for him - and why do people in general buy Wintel? because that's the decision seller income depends on.