Even as enterprises try to purge their last Windows XP machines, Gartner analysts today urged organizations to start planning for the end of Windows 7.

"Now I need to worry about the next version?" Michael Silver of Gartner rhetorically asked today. In fact, yes. "Objects in the future are closer than they appear," he quipped.

Microsoft has pledged to support Windows 7 until Jan. 14, 2020, or five years and five months from today. The company's "Mainstream" support -- the front end of a 10-year stretch -- ends Jan. 13, 2015, but the firm will continue to provide security patches for the popular OS for another five years after that in its "Extended" support phase.

With more than five years left on the support clock -- and with many enterprises having just wrapped up their migration to Windows 7 -- why start planning now?

"While this feels like it's a long way off, organizations must start planning now so they can prevent a recurrence of what happened with Windows XP," said Silver and Gartner colleague Stephen Kleynhans, the two analysts who authored a recent report for the firm tagged "Plan Now to Avoid Windows XP Deja Vu With Windows 7."

In fact, said Silver, the time between the likely launch of Windows 8's follow-up -- at the moment called "Threshold" by many, including Silver -- and the end of Windows 7's support is approximately the same as the timespan between Windows 7's debut and XP's retirement: About four-and-a-half years.

And everyone knows how that turned out.

Not well: According to Gartner's surveys, nearly 25% of the PCs in organizations -- private enterprises, government agencies and the like -- were still running XP in April when Microsoft pulled the patch plug. That same 25% was cited by Web metrics vendor Net Applications as the percentage of the world's personal computers running XP last month.

Having a plan, Silver stressed, could help organizations avoid a repeat of XP's expensive end-of-support scramble. And time is ticking.

"Microsoft will soon start talking about Threshold, at least they need to start talking about it soon if they plan on shipping it next year," said Silver in an interview. "They need to give customers an idea of what the road map is going to be."

And when Microsoft starts talking, organizations should start listening, if only to try to figure out whether there's enough difference between Threshold and the Windows 8 flop to commit to the former. If Threshold is simply a warmed-over Windows 8, then enterprises must know that, too -- and as soon as possible, so that they can postpone migration plans entirely and hope that whatever comes after Threshold is palatable.