Microsoft is offering Windows XP Service Pack 3 (SP3) for public downloading, two weeks after the company handed it to several thousand invitation-only testers.

"We're broadening the availability of the release candidate in order to receive further user feedback prior to the release of Windows XP SP3," said a company spokeswoman.

On 7 February, Microsoft seeded Release Candidate 2 (RC2) with the 15,000 or so testers who had been working with SP3 for several months. At that time, the company said nothing about taking the version public.

This is just the second time that all Windows XP users have had the chance to try out SP3, the last scheduled major update to the six-year-old operating system. The only other public posting was of SP3 RC in December.

Microsoft, however, has followed precedence. Earlier this year, it did the same thing - sent code to its beta testers, then released it to all comers - during the run-up to finalising Windows Vista Service Pack 1. In fact, although Microsoft has stuck to the vague schedule of delivering XP SP3 some time in the first half of 2008, Vista's pattern may signal that the XP service pack release is imminent.

The company said that the SP3 RC2 download would be posted on the Microsoft Download Center. A link to it may also appear on this TechNet page.

Once SP3 ships, the next major milestone for Windows XP is 30 June, when the popular operating system is expected to fall off the reseller and retail availability list.