Windows XP quietly turned 10 years old Wednesday, a milestone for the still-popular operating system that powers nearly half the world's PCs.

Microsoft did not celebrate the anniversary, eschewing any congratulatory blog post or press release.

On Aug. 24, 2001, Microsoft shifted Windows XP's status to RTM, for "release to manufacturing," a term it uses to mark the end of development and the move to duplication and release to computer makers. XP reached retail in October 2001.

One analyst questioned whether it was really the right anniversary to celebrate.

"The Windows XP that people loved wasn't [the original 2001] XP, it was XP SP2," said Michael Cherry, an analyst with Kirkland, Wash.-based Directions on Microsoft, a research firm that covers only Microsoft.

Windows XP SP2, or "Service Pack 2," shipped three years later, in August 2004.

That edition, which Microsoft itself acknowledged was out of the ordinary for one of its service packs, added new functionality and dramatically boosted XP's security. Among the security-oriented changes were a revamped firewall that was switched on by default, a new Security Center that monitored bundled and third-party firewall and anti-virus defenses, and the introduction of DEP, or "data execution prevention," Microsoft's first anti-exploit technology.

Full story: Computerworld