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.

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.