Since September 2004, Microsoft has launched a test tool named Windows Genuine Advantage (WGA) to check whether the copy of Windows a PC is using is properly licensed.

Windows XP users have had to validate their operating system, since last July, to be able to download additional resources (software), such as Windows Defender, Windows Media Player or Internet Explorer 7.

Starting Tuesday, WGA is supposed to be sent to millions of people in the United States, United Kingdom, Malaysia, Australia and New Zealand, Microsoft said Monday. Following download and installation of the WGA Notifications tool, users of a pirated copy will see alerts at startup, login and during their use of the operating system. The alerts read: “This copy of Windows is not genuine; you may be a victim of software counterfeiting.” while those who use a legitimate copy of the software won’t see any messages, Microsoft said.

Download and installation is optional and users will be able to uninstall it at anytime, said David Lazar, director of the Windows Genuine program at Microsoft. They can also suppress the alerts by right-clicking on them when they appear during the running of Windows.