The New York Times points out that in the five years since the last revision of Windows, Apple has released four new versions of its OS, beating Microsoft with many features such as widgets and desktop search. The question, naturally, is why? And the answer may be that Microsoft has simply gotten too fat.

Microsoft owns the computer desktop, with a virtual monopoly. Windows runs on about 330 million PCs around the world. And whether or not Vista gets out this year, or next year, or the year after, when the vast majority of people buy PCs, those PCs will run Windows.

With that kind of built-in revenue engine — plus others, such as Office — there’s no sense of urgency to what Microsoft does. Vista is delayed by a year? Yawn. That’s OK; the company will still rake in the cash.

I was around in the early days of the PC, and I remember when another big company had a virtual computing monopoly and built-in revenue engines — IBM. Why worry, the IBM thinking went. If people need computing power, they’ve got only one place to go — after all, no one ever got fired for buying an IBM product.

Today no one ever gets fired for buying a Microsoft product. But if Microsoft keeps on the track it’s going, that may not be the case tomorrow. Google and other smarter, nimbler competitors are beating out Microsoft, and unless the company recognizes that, it will become about as exciting as your local water company, and its revenues may plummet.