Windows XP has fewer than 500 days left to live, according to Microsoft and third-party countdown clocks.

Microsoft will end support for XP on April 8, 2014, when it will issue a final security update for the 11-year-old operating system.

On Saturday, the retirement countdown clocks offered by Microsoft and others flipped from 500 to 499 days, or a shade under 17 months.

Microsoft provides a countdown gadget for Windows XP's support demise. Ironically, the gadget runs only on Windows 7, the 2009 OS that most customers have adopted after departing XP.

Camwood, a U.K.-based company that specializes in helping businesses migrate their machines to newer operating systems and software, has posted a similar clock on its website. Like Microsoft's gadget, Camwood's also showed 499 days remaining on Saturday.

When Microsoft pulls XP's plug, it will have maintained the operating system for 12 years and five months, or about two-and-a-half years longer than its usual practice. That's also a record, replacing the previous Methuselah, Windows NT, which received 11 years and 5 months of support.

XP's long life was caused in large part by the debacle that was Windows Vista, an oft-delayed operating system that was ultimately rejected by most XP users for being buggy, sluggish or lacking in driver support. Instead, those customers waited for the next iteration, Windows 7, which has been as much a success as Vista was a failure.