It's a year and a day since Microsoft pulled the plug on Windows XP by refusing to sell new copies of the operating system after June 30 2008.

Microsoft's move caused a public outcry, with users demanding that the company keep XP available alongside Vista for the many users who were frustrated by ease-of-use, compatibility, and retraining issues.

Microsoft did eventually relent and said XP would remain available in a variety of specialty channels. For example, Microsoft let companies that build 'white box PCs' for customers sell new XP licences until February 2009 .

It also said PC makers could 'downgrade' new systems to XP, so Dell and HP continue even today to offer XP on a selection of models. (But such OEM downgrades will end on July 31, 2009.)

Enterprises with corporate-wide licences and any user with a full or upgrade licence has 'downgrade' rights on their PCs to install XP Pro over Vista Business. And it has kept XP available for netbooks, though largely because most cannot run Vista. Plus, stores such as Amazon continue to sell XP, using inventory acquired before Microsoft's June 30, 2008, general kill date for the OS. (Microsoft's technical support for XP will continue to April 2014 in some cases.)

Gartner analyst Michael Silver attributes XP's persistence, and Microsoft's compromises over killing it outright, to that public outcry. But now that Windows 7 is less than four months away, is it time for XP users to move to a Windows 7 future and finally let XP go?

The resistance to Vista was historic

Microsoft officials periodically tell the public that Vista is the most successful version of Windows ever sold, but the numbers don't coroborate those claims. Officially, Microsoft has no comment on the rate of Vista adoption, and a spokeswoman said Microsoft doesn't stand behind the claims of its employees.

Gartner's Silver said that when Microsoft does talk Vista numbers, it talks about shipped licences. But anyone who 'downgrades' to XP was still shipped a Vista licence, which distorts the numbers - significantly.

An analysis of thousands of PCs worldwide, though concentrated in North America, shows that more than half of business PCs have downgraded to XP, as have about 12 percent of consumer PCs (which have very few options to 'downgrade' as compared to business PCs).

The data is based on the XPnet community of PCs, which counts 17,000 systems that contribute data on their configurations and performance attributes.

NEXT PAGE: Will windows 7 have an adoption rate as low as Vista?

It's a year and a day since Microsoft pulled the plug on Windows XP by refusing to sell new copies of the operating system after June 30 2008, but with Windows 7 just four months away, should XP users move towards a new OS?

Gartner's research backs XPnet's findings, showing a significantly lower adoption rate in enterprises of Vista compared to that of Windows 2000 and XP at the same points in their lifecycles. In the 18 to 24-month period after Windows 2000's release, 12 percent of enterprise PCs ran Windows 2000.

For XP at that period, 14 percent of enterprise PCs ran Windows XP. But at the same point in Windows Vista's lifecycle, only six percent of enterprise PCs are running it. Gartner's Silver expects Windows 7 to follow the strong adoption pattern of Windows 2000 and XP.

"80 percent of our clients are telling us they've decided to skip Vista," he said.

Is it time to embrace Windows 7?

By all reports, Windows 7 fixes many of Vista's sins and adds compelling new capabilities to the mix. Tests show that Windows 7 is fundamentally no faster than Vista; they also show that as applications get more multicore-aware, Windows 7 has more headroom for performance growth than XP does.

"Windows 7 has longer legs than Windows Vista or XP, especially on multicore," said blogger Randall C Kennedy who runs the XPnet community.

"This, combined with improvements in background task scheduling and some timely kernel tweaks, provides for an improved users experience - even on lower-end PC hardware, like netbooks. However, whether or not it'll be enough to help Windows 7 overcome Vista's stigma remains to be seen."

Although Gartner's Silver says Windows 7 is a worthwhile upgrade, he recommends that enterprises wait 12 to 18 months before migrating to Windows 7, so IT can test the OS on their current and planned PCs, verify software compatibility, and understand the implications of software vendors' Windows 7 plans.

For example, Silver has seen some software vendors consider using the Windows 7 launch to raise prices via Windows 7-certified upgrades. He also warns IT to inventory its web applications designed for Internet Explorer 6, which are likely to not work properly under the Vista-oriented IE7 or Windows 7-oriented IE8.

IT must also work through Microsoft's array of software licences, while also navigating moves the company seems to be making to steer customers to pricier licensing options.

For example, two weeks ago, Microsoft had planned to limit the ability to downgrade to XP new PCs bought before April 2010, which could force enterprises to upgrade to Windows 7 before they are ready. However, Gartner's Silver publicly slammed the plan, which led Microsoft to change it so that downgrades are allowed on new PCs bought through April 2011.

Last week, Microsoft announced new PCs bought since June 26, 2009, could get a free upgrade to Windows 7 when it shipped - but it limited businesses to 25 free upgrades. Businesses that pay extra for Microsoft's Software Assurance plan are free to upgrade the OS at any time, as a benefit of what is essentially a subscription plan.