Windows XP users continued to put their old hoss OS out to pasture in April, statistics showed, but the now-unsupported operating system still powered more than one in every four personal computers on the planet.
According to Web analytics company Net Applications, Windows XP dropped 1.6 percentage points in "user share," an estimate of the fraction of the world's computer owners that run a specific operating system, to end April with 26.1% of all desktop and notebook systems. It was the second consecutive month that XP shed significant user share.
Windows XP accounted for about 28.8% of all Windows-powered PCs last month. The difference between the numbers for all personal computers and only those running Windows was due to Windows powering about 91% of all personal computers, not 100%.
Microsoft delivered the final public security update for Windows XP on April 8. Since then, users have faced the likelihood that cyber criminals will dig up new vulnerabilities -- perhaps by examining fixes for still-supported editions -- and unleash exploits on PCs still running the retired OS.
Hackers already know their first such opportunity: A vulnerability in Internet Explorer (IE) spotted last week.
Microsoft will probably issue a fix for the IE bug -- which affects every edition of the browser -- before or on May 13, this month's Patch Tuesday. But the patches for IE6, IE7 and IE8 -- the three editions supported by Windows XP -- will not be offered to XP owners.
With patches in hand, attackers can compare the fixed code with the vulnerable code, locate the source of the flaw and then write an exploit to use against XP. In the case of the IE vulnerability, it may be even easier; if the in-the-wild exploit goes public, which it will almost certainly do, less-astute cyber criminals can simply copy it, or modify it if necessary, before targeting XP PCs.
Even with the two-month decline of Windows XP, a large minority of machines will be running the 13-year-old OS for months or perhaps even years to come. Computerworld now projects that XP will power about 19% of all personal computers at the end of 2014 and 14% at the mid-point of 2015.
The biggest beneficiary of XP's user share decline in April was the newest Microsoft operating system. The combination of Windows 8 and Windows 8.1 gained nine-tenths of a percentage point to end April with 12.2% of all personal computers, or 13.5% of only those running Windows. It was the largest one-month surge by Windows 8/8.1 since December 2013.
Of the combined user share, the newer Windows 8.1, which received a feature update last month, accounted for 48% of the total. Windows 8.1 will overtake its predecessor in user share this month to become the more dominant of the pair.
Windows 7, the 2009 stalwart expected by many to go into retirement as grudgingly as did XP, also added user share as XP's declined. Windows 7 climbed six-tenths of a percentage point to end April with 49.4% of all personal computers, and 54.4% of only those running some form of Windows.
That increase was less than half of Windows 7's March gains, perhaps hinting at the beginning of the end of enterprise migrations. Businesses still stuck with some XP PCs have been replacing them with ones running Windows 7, not Windows 8 or 8.1. Analysts expect that companies will standardize on Windows 7 for several years, and may be hard to pry from the OS when its support ends in 2020.
Gregg Keizer covers Microsoft, security issues, Apple, Web browsers and general technology breaking news for Computerworld. Follow Gregg on Twitter at @gkeizer, on Google+ or subscribe to Gregg's RSS feed . His email address is firstname.lastname@example.org.