Microsoft last week painted Windows XP consumer and small business customers into an even smaller corner when it said it could not recommend that they upgrade to Windows 8.1, the update to Windows 8 slated to ship Oct. 18.

"Windows 8.1 is not designed for installation on devices running Windows XP or Windows Vista," said Brandon LeBlanc, a company spokesman, in a Sept. 17 blog announcing the retail prices for Windows 8.1. LeBlanc also said the new update was "not recommended" for hardware now running Windows XP or Vista.

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Microsoft's change of heart -- last year it pitched Windows 8 upgrades to XP owners -- leaves the latter with just one upgrade path: To Windows 7.

Upgrading from Windows XP is a concern for not only Microsoft but also for its customers; the company plans to serve the final security update for the 12-year-old operating system on April 8, 2014, little more than six months from now.

But dropping Windows 8.1 as an option for Windows XP users means Microsoft almost certainly will extend a looming deadline for sales of Windows 7.

Microsoft has policies in place that shut off sales to retailers of an older operating system one year after the launch of its successor, and which stop shipping the previous Windows edition to OEMs for installing on new PCs two years after a new version launches. If Microsoft stuck to those rules, it would halt sales to retailers of Windows 7 after Oct. 30, 2013 and quit shipping Windows 7 to OEMs after Oct. 30, 2014.

The company website that marks those deadlines, however, doesn't yet specify "end of sale" dates for Windows 7 in retail or on new PCs, even though the retail cutoff is just five weeks away.

That omission is probably not an oversight. For if Microsoft hewed to its rules, it would effectively be telling XP owners that from November until April 2014, the stretch when XP will still be supported, there will be no upgrade path for them except buying a new device.

While Microsoft could certainly take that step -- it would actually prefer that XP PC owners simply ditch their hardware and step up to Windows 8.1 with a new tablet or PC -- it's unlikely to. First, Microsoft has been beating the dump XP drum long and loud, with even top executives joining in.

"We have plans to get [XP's share] to 13 percent by April when the end-of-life of XP happens," said Kevin Turner, Microsoft's COO, during last week's half-day presentation to Wall Street. "This has been a major and multi-year initiative for us, and one that we've worked very hard on to make sure we can execute towards."

Second, the backlash to Microsoft nullifying an upgrade path would be swift and probably fierce; there has long been a contingent of Windows users who see conspiracy in every upgrade, believing that Microsoft is "forcing" them to spend more money.

(It doesn't help Microsoft that on occasion it seems to do just that, as the recent Office 2010 Starter update snafu showed.)

Admittedly, there is no rule that says Microsoft must offer an upgrade path for an aged operating system until its support lifecycle ends. But Windows XP is not just any edition: Not only is it the longest-supported of any Microsoft operating system, but it's also the one with the largest user base this close to retirement.

According to Web metrics company Net Applications, XP powered 33.7 percent of all personal computers worldwide in August, or 37 percent of all systems running Windows. Rival StatCounter, which is the measurement firm that Turner cited last week when he claimed XP had a 21 percent share and would be down to 13 percent by next April, figured the old OS powered 20.6 percent of the world's personal computers.

While the extension of Windows 7 sales to retailers may be construed by some as another proof of Windows 8's lackluster uptake, that's probably more palatable to Microsoft than the furor it would raise by yanking Windows 7, at least officially, from shelves.

"Officially" is the key word, as Microsoft's sales lifecycle rules notwithstanding, Windows 7 will remain available at online outlets long after the Redmond, Wash. company's deadline. That's because retailers stock up on an OS before they're cut off from the supply. Amazon.com, for example, continues to fulfill orders -- through third-party vendor partners -- for Windows Vista, which officially met its retail end in Oct. 2010, and even Windows XP, which was supposed to disappear from retail in 2008.

Microsoft, in fact, posts a caveat of its own on its sales lifecycle website: "When the retail software product reaches its end of sales date, it can still be purchased through OEMs (the company that made your PC) until it reaches the end of sales date for PCs with Windows preinstalled," Microsoft states.

Hewlett-Packard, for instance, currently carries Windows 7, although it charges full list price, unlike Amazon, NewEgg and other e-tailers, which discount the OS.

Diehard XP users in larger businesses won't have any trouble upgrading to Windows 7, as the deadlines don't apply to them: Companies with volume license and Software Assurance agreements are allowed to replace XP with another edition of Windows, assuming the hardware supports the newer.

But consumers and small businesses -- the latter typically purchase PCs and upgrade existing machines much like consumers -- will be in a pinch if Microsoft shuts the Windows 7 ... well, window.

Microsoft did not reply to questions today, including whether it will extend the Windows 7 retail sales deadline.

Gregg Keizer covers Microsoft, security issues, Apple, Web browsers and general technology breaking news for Computerworld. Follow Gregg on Twitter at @gkeizer, or subscribe to Gregg's RSS feed . His email address is gkeizer@ix.netcom.com.

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This story, "Microsoft puts Windows XP laggards in a pinch" was originally published by Computerworld .