Microsoft on Friday introduced a new pilot program to encourage refurbishers to install legitimate copies of Windows XP on used PCs.

The new Microsoft Authorized Refurbisher (MAR) program offers a discount off the retail price of Windows XP, along with deployment tools to help refurbishers reinstall Windows and all of the relevant drivers on renewed PCs in as little as 15 minutes, said Hani Shakeel, senior product manager of the genuine Windows product marketing team.

When MAR is fully expanded, it will also help stem what Microsoft acknowledges as widespread flouting of Microsoft's XP licensing rules by price-pressured refurbishers.

"There's a range of behavior. Definitely, what you're describing is happening," Shakeel said.

Observers say MAR also attempts to ameliorate another risk: that refurbishers, frustrated by the high cost and difficulty of following Microsoft's arcane Windows licenses to the letter, will simply install a free Linux operating system on renewed PCs instead.

Some resellers "are saying, 'We're just going to ship this stuff out with Ubuntu Linux,'" said Adam Braunstein, an analyst with the Robert Frances Group.

Braunstein estimates that for now, no more than one in ten refurbished PCs goes back out for sale sporting Linux rather than Windows. But Microsoft is worried.

"There are pieces of the armor that are pretty rapidly deteriorating," he said.

And the first two contestants are...

Two large refurbishers have been initially selected to participate in MAR: Columbus, Ohio-based Redemtech and Austin, Texas-based TechTurn.

Microsoft has long encouraged the donation and reuse of older PCs, albeit in a limited way. Its Community MAR program lets PC recyclers obtain cheap copies of Windows that they could use to install on used computers.

But the catch was that those licenses were only available for PCs destined for use by charities, schools and other non-profit groups. As a result, only 200,000 refurbished PCs worldwide last year benefited from the Community MAR program, according to Microsoft.

Meanwhile, up to 28 million refurbished PCs will be sold this year, making up 10 percent of the global PC market, according to Microsoft's Shakeel. Nearly all are destined to consumers and smaller companies.

Many of those PCs shipped will be violating some aspect of Microsoft's complicated End User License Agreement (EULA) for Windows. For instance, most refurbishers will assume that they can reinstall Windows onto a recycled PC using the license number on the original Certificate of Authenticity (COA) that shipped with it. In fact, Microsoft requires that refurbishers also have the original Windows installation CD.