Microsoft says the next version of Windows will go on sale in time for the holiday shopping season.
The software maker published an almost-final version of Windows 7 - the so-called Release Candidate last week, a sign it would be ready before the official January 2010 deadline.
Windows 7 will replace the much-maligned Vista, which launched too late for the 2006 holiday season.
Microsoft had guaranteed free Vista upgrades to people who bought new XP computers for the holidays.
But Microsoft was criticised when it turned out some of those PCs weren't powerful enough to run a full version of Vista.
Having Windows 7 in time for the Christmas holidays may help boost PC sales, which have been stalled by the recession.
The Windows 7 Release Candidate - which is not a full retail version of the operating system - is available for download from Microsoft here.