The scheme asks visitors to the Download Center, Microsoft Update or Windows Update to check that the Windows XP or Windows 2000 operating system installed on their machines is a legitimate and licensed copy.
A program is downloaded to visiting PCs (in the form of an ActiveX control) to perform a scan.
If a counterfeit copy of Windows is detected, users are given two choices:
If a legitimate copy is found, Microsoft stores a special download key on the PC for future use.
Microsoft stresses that the validation process does not collect any information that can be used by Microsoft to identify or contact the user.
The company also confirmed that security updates will still be provided to all computer users, regardless of whether or not they have validated their Windows software. This is to prevent viruses and other malware taking advantage of non-updated computers.
Microsoft says WGA is part of its ongoing battle against software counterfeiting and will allow genuine users to have easy access to updates, added-value software offerings and confidence that their software is authentic.
"During the 10-month pilot of WGA, we have been very encouraged by the large number of customers – more than 40 million in all – who chose to participate in WGA because they were concerned about piracy and wanted a way to determine whether their Windows software was genuine," said Will Poole, senior vice president of the Windows Client Business at Microsoft.
"It also became clear that customers want to take advantage of special offers reserved for genuine users, with the peace of mind that their software will deliver the features, options and performance they need," he added.