Ten years after it was introduced, Windows XP is still the most popular computer operating system, according to figures from Net Applications. About 54 percent of PCs are still running XP, while about 24 percent are on Microsoft's 18-month-old Windows 7 system. Just 10 percent are using Vista, the system Microsoft launched and quickly shelved in between XP and Windows 7.

While many computer users—especially those on netbooks or older PCs—may prefer to stick with XP, users of earlier versions of Windows should check to make sure their security settings are up-to-date. Microsoft stopped issuing security updates for Windows XP with Service Pack 2 last July, and will stop supporting the more recent Service Pack 3 in April 2014. If you're still running a version of Windows XP with Service Pack 2, you should install Service Pack 3, which is available as a free upgrade from Microsoft.

Newer versions of Microsoft's Internet Explorer web browser, with enhanced security and anti-tracking features, will only work with Windows 7, though Mozilla Firefox's latest edition, with similar features, works with XP.

Watch this space for our upcoming State of the Net report, detailing the latest in computer and internet security trends.

Microsoft shifts 350 million Windows 7 licenses in 18 months, XP still king [Digital Trends]
Windows End of Support Information - Windows Help & How-to [Microsoft]