Microsoft is preparing a piracy lock on two of its download websites, requiring all Windows XP and Windows 2000 users to validate their copy of Windows as genuine before downloading software.

The lock will be placed on the Microsoft's Download Center and Windows Update websites, which offer applications such as Windows Media Player and the new Windows AntiSpyware product as well as security updates for Microsoft products.

Validation will not be required for Windows Automatic Updates, said David Lazar, a director in Microsoft's Windows Client group. Automatic Updates is a feature in Windows that is used to download and install security updates to Microsoft software.

Before requiring all users to validate their copy of Windows at an unspecified date in mid-2005, Microsoft on 7 February plans to expand the current Windows Genuine Advantage test to increase the number of language versions of Windows XP covered from five to 25 and cover most downloads on the Download Center, the company said.

Also, starting on 7 February Download Center visitors using Norwegian, Czech and Simplified Chinese versions of Windows will be required to participate in the test and validate their copy of Windows, Microsoft said. Users who discover that they have a pirated copy of Windows will be offered a genuine version of Windows at a discount.

To qualify for the discount users will have to prove that they were duped into buying an illegal version of Windows while they thought they were buying a legitimate copy, Lazar said. This could be done, for example, by submitting a piracy report, proof of purchase or a CD-ROM, he said.

"Our goal is not to now have an amnesty or to have a discount version of Windows generally available. We merely want to take care of any customer who may have been cheated and we want to recognise that they spent some money already, even if it was not paid to Microsoft," Lazar said.

Microsoft has the right to ensure that users have a genuine copy of Windows, particularly before adding anything to the operating system or servicing it, said Michael Cherry, a lead analyst at Directions on Microsoft.

Requiring a genuine copy of Windows not only protects Microsoft, but also law-abiding Microsoft partners who otherwise face unfair competition from illegal software, Cherry said.

The Windows Genuine Advantage checking mechanism is anonymous, according to Microsoft. It includes an ActiveX control on the client side and the Windows Product Activation service on the Microsoft side. A user has to install the ActiveX control and enter the Windows product key, which on new PCs bought with the operating system is typically found on a sticker affixed to the PC.

This is not the first time that Microsoft is checking whether installed copies of Windows are legitimate. Windows Update already checks for certain volume license keys that are known to be used illegally to activate copies of Windows. The Windows Genuine Advantage check looks for more known bad license keys, Lazar said.

Software piracy is a major issue for Microsoft. In the United States alone, almost a quarter of all Windows users run an illegal copy. However, one problem the software maker faces is that many users don't know that their copy of Windows is illegal.

"In developed countries, the majority of customers who are running pirated software are doing so unwittingly," said Bonnie MacNaughton, a senior attorney at Microsoft.

"Most of the counterfeits that we see that are sold in the developed markets are very good pass-offs of our software that most customers would not be able to tell the difference between those and our genuine software," she said.

That's where Microsoft has some work to do, said Directions on Microsoft's Cherry. "Microsoft is not doing enough proactively to educate people about what they should look for when they are buying a computer to ensure that they do get a genuine copy of Windows," he said.

Microsoft has adopted a multi-pronged attack on software piracy. The company is selling cheaper versions of Windows in certain Asian countries where software piracy is widespread (although the company is also under attack in Asia from the prevalence of Linux PCs) and is also working closely with law enforcement to stop those who manufacture or sell illegal copies of its products.