Microsoft has been banging the Windows XP upgrade drum for years, but stepped up the campaign in 2012, including starting a "two-year countdown" to the demise of security support. Last month, Microsoft was blunt, saying "If your organisation has not started the migration to a modern PC, you are late."

Windows XP exits all support, including monthly security patches, in April 2014.

In a blog post Thursday, Erwin Visser, a senior director for Windows, used data collected by IDC to make Microsoft's upgrade case.

"The bottom line...[is that] businesses that migrate from Windows XP to Windows 7 will see significant return on investment," said Visser.

Microsoft sponsored the survey) conducted by IDC, which in turn interviewed nine enterprises or large organisations to drill into the support costs of XP and Windows 7.

According to IDC, an amazing 42 percent of the Windows "commercial" installed base, or anything other than consumers' home machines, was Window XP, making Microsoft's job of moving everyone off the old OS by its April 2014 retirement nearly impossible.

In fact, IDC projected that if current trends continue, 11 percent of the enterprise and educational Windows installed base will still be running XP when Microsoft stops patch delivery in 23 months.

And those XP machines costs organisations considerably more to support than comparable PCs running Windows 7.

One reason for the increased costs for supporting Windows XP is that it's typically running on older hardware that, independent of the OS, is more expensive to simply keep running.

XP more expensive to support in every category

The magic milestone is after the three-year mark, when "costs begin to accelerate" because of additional IT and help desk time, and increased user downtime due to more security woes and time spent rebooting, said IDC.

IT labour costs jump 25 percent during year four of a PC's lifespan, and another 29 percent in year five, IDC noted, while user productivity costs climb 23 percent in year four and jump 40 percent during year five. Total year five costs are a whopping 73 percent higher than support costs of a two-year-old client.

However, the operating system also plays a major role in the cost differences, said IDC, with XP more expensive to support in every category the research company surveyed.

Organisations reported that they spent 82 percent less time managing patches on Windows 7 systems than they did on Windows XP, 90 percent less time mitigating malware, and 84 percent less help desk time.

Benefits were also striking for Windows 7 users' productivity compared to XP. Windows 7 users wasted 94 percent less time rebooting their computers and lost 90 percent less time due to malware attacks.

On the IT side, the savings of Windows 7 mount dramatically, IDC said.

"IT activities account for 11.3 hours of time spent per PC per year when using Windows XP," the research group said. "Shops that have moved to Windows 7...spend 2.3 hours per PC per year on maintaining those systems."

IDC did the math, and concluded that for every 230 PCs running Windows 7 rather than XP, an organisation could shift one full-time IT person to other work. Or conceivably do without him or her entirely.

The Microsoft-commissioned report also painted a rosy return-on-investment (ROI) picture for companies who do ditch XP for Windows 7. By IDC's calculations, the acquisition of a new PC - one where Windows 7 is retained as the OS rather than being downgraded to XP - pays for itself in one year and generates almost $1,000 more in savings from reduced IT costs and worker downtime over a three-year span.

"The migration from Windows XP to Windows 7 yields a 137 percent return on investment over a three-year period," claimed IDC.

Windows XP have a shortening upgrade window - no pun intended - and not only because of the April 2014 end to all support. Microsoft is expected to launch Windows 8 this fall, a time when most new PCs will then also be pre-loaded with the OS by computer makers, or OEMs.

That will not immediately strike Windows 7 from the rolls, but it does start a couple of clocks ticking: OEMs can continue to sell Windows 7-powered PCs as long as two years after Windows 8's launch, but the older operating system will disappear from most retail outlets one year earlier, or in the fall of 2013.

Organizations that have Software Assurance (SA) agreements - the Microsoft-sold software insurance policy that lets firms upgrade to every new version of a specific product released during the life of the deal - can downgrade any Windows 8 PC to Windows 7. But SA is almost exclusively an enterprise program.
XP still accounts for 46.1% of OS going online

Smaller firms that buy Windows licenses at retail, likely in the form of a new PC, can also downgrade from Windows 8 to 7, but only if the new system is pre-installed with Windows 8 Pro, the higher-end edition. They will also need media - a DVD or flash drive - containing Windows 7 Professional to complete the downgrade. If smaller shops wait too long, they may find it difficult to locate a seller for the latter after late 2013.

Likewise, while Windows XP Professional can be upgraded to Windows 7 Professional, companies sans SA also require a copy of the newer OS. The same end-of-retail caveat for Windows 7 applies to them as well.

Microsoft has been dissing Windows XP for some time, but the ROI report was its first argument that stressed dollars and cents.

In June 2011, a Microsoft manager said it was "time to move on" from Windows XP; earlier that year an executive on the Internet Explorer team belittled XP as "lowest common denominator" when he explained why the OS wouldn't run the then-new IE9.

The company has not yet turned on Windows XP like it has on the 11-year-old Internet Explorer 6 (IE6). For more than two and a half years, Microsoft has urged users to give up IE6, going so far in March 2011 to launch a deathwatch website that tracks IE6's shrinking share.

It wouldn't be a surprise if Microsoft followed suit with Windows XP once the OS drops to a more manageable share mark: According to Web metrics company Net Applications, XP accounted for 46.1 percent of all operating systems used to go online in April.

If XP continues to shed share at its last-12-months' pace, it will still own a 17.6 percent share in April 2014, when it drops off support.