What do the future of computing, a hurricane-ravaged home, and Fred Flintstone's car have in common? If "no windows" is your answer, step on up and claim your prize.

Microsoft's (NASDAQ:MSFT) flagship operating system is under fire these days. Last month, market watcher Forrester Research claimed that just 6.3% of surveyed corporate computer users had upgraded to Windows Vista in 2007. Now you have rival research firm Gartner also warning that Microsoft's days on top are numbered.

In a "Windows Is Collapsing" presentation this week, a pair of Gartner analysts claimed that businesses have been slow to embrace the new platform, given its chunky system requirements and the Web's role in making popular applications operating-system-agnostic.

The first point is valid. Those thicker spec sheets had companies such as Dell (NASDAQ:DELL) and Intel (NASDAQ:INTC) braced for hardware upgrades that never came.

The second point is equally valid and perhaps even more damaging, because it also speaks to the future of Microsoft's other workhorse, Microsoft Office.

Cloud computing's initial appeal is economical. It is typically cheaper to go with Salesforce.com (NYSE:CRM) for enterprise software applications than with more conventional commercial solutions. Naturally, the free word-processing and spreadsheet programs from companies such as Google (NASDAQ:GOOG) are also easier on the pocket than Microsoft is.

The more lingering appeal is in the convenience of having your files follow you wherever you have Web access, since the files are saved on the provider's servers.

That's a double-whammy for Microsoft. If you don't need to run Office, you don't need to run Windows. Any operating system will do. Nearly any Web browser will do. This is partly why Apple (NASDAQ:AAPL) and dirt-cheap Linux-based systems have been selling briskly these days. The same Microsoft that once inherited users now has to go out and earn them.

No one is painting Microsoft as an underdog quite yet, but it's not the universal favorite it used to be. Some may argue that Microsoft took a deep look in the mirror, saw what it's going to look like in a few years, and decided to go the Microhoo route, but that doesn't make sense. Yahoo! (NASDAQ:YHOO) isn't a hotbed of Web-based apps. If that were all that Microsoft wanted, it could have paid far less and nabbed Salesforce.

Either way, Microsoft has to be concerned that a pair of market-research firms are jockeying to see which can be the first to plant their flag on Vista's grave.

What do Redmond housemaids, hurried auto-body shops, and computer users have in common? They just don't do Windows like they used to.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.