Microsoft this week denied reports that Windows XP Service Pack 2, which includes extensive security fixes, will be available for users running pirated versions of Windows.

The Asian Computer Times recently reported that Microsoft will make SP2 available to all users. The publication quotes Barry Goffe, Microsoft Group Product Manager, as saying, "It was a tough choice, but we finally decided that even if someone has pirated copy of Windows, it is more important to keep him safe than it is to be concerned about the revenue issue ... Having these unsecured users means bigger worm and virus outbreaks - which also impacts the Internet and consequently, our legitimate users as well."

Microsoft CEO Steve Ballmer said last month that Microsoft makes security patches available to all users, even pirates, as a means of limiting the spread of viruses and worms.

But Microsoft said this week that Service Pack 2 will, before installation, check the operating system's Product ID against a list of known pirated ID numbers. If the operating system comes up as illegitimate, the update won't install.

A Microsoft spokeswoman said in an E-mail: "Using genuine software is an important part of keeping systems secure and running smoothly, because it means continued access to the latest security enhancements and product updates. Licensed versions of Windows XP, coupled with the upcoming Service Pack 2, will represent Microsoft's most secure desktop operating system."

The spokeswoman declined to comment further.

Rob Enderle, principal analyst at the Enderle Group, said Microsoft can't afford to let pirates use the patches, despite the potential benefit to all users. "One of Microsoft's value propositions for purchasing the software rather than stealing it is that you can get patches and support," he said. "They don't want to break the value proposition. They are not in the business of free software."

Supporting pirated software could also open Microsoft to legal liability.

Windows XP Service Pack 2, which is due out in late summer, is a comprehensive update to Windows that includes fixes to network utilities to make them less vulnerable to attack, and a new security control panel designed to help beginners keep their computers secure.

Service Pack 2 is also designed to help ameliorate a major reason why viruses and worms spread: users fail to install patches against the malicious code in a timely fashion. Service Pack 2 reconfigures Windows so that subsequent patches will automatically be downloaded and installed. Users can switch off the automatic updating, but Microsoft hopes that more users will install the updates if installing updates is the default behavior for Windows. .