CIOIN

Windows 7 has expanded its lead over Windows Vista with more than 350 million licenses sold after 18 months on the market, Microsoft said Friday. But Windows XP, older than both Vista and 7, still captures about half of the desktop operating system market with Mac and Linux far behind.

"Analyst firms like IDC estimate that more than 90% of businesses are currently in progress with their Windows 7 migrations," Microsoft official Brandon LeBlanc blogged Friday. "And we've seen that companies who have deployed Windows 7 save an average of $140 per PC per year -- showing a 131% return on investment in just more than 12 months."

Just as Microsoft launched a kill-IE6 campaign to highlight advances in Internet Explorer 9, Microsoft is offering a "Windows XP End Of Support Countdown Gadget" that can be installed on your desktop to count down the end of support in 2014.

Oddly, the gadget is only supported on Windows Vista and Windows 7, even though people who have upgraded from XP don't have any reason to worry about the OS end-of-life date.

Convincing users that XP is out of date, in part by limiting IE9 to Vista and Windows 7, could help continue to boost sales of what Microsoft calls "the fastest selling operating system in history."

But while Windows 7 has passed the 10-year-old Windows XP in U.S. usage share, it's far behind XP worldwide.

Net Applications gives Windows XP a 54.39% market share, followed by Windows 7 at 24.17% and Vista at 10.56%. Mac and Linux combine for a little more than 6%.

StatCounter, another market share tracker, puts Windows XP share at 47.32%, but still far ahead of the 30.6% garnered by Windows 7. While the smartphone and tablet markets are being dominated by non-Microsoft operating systems, when it comes to desktops and laptops it is still very much a Windows world.