Windows Vista of January 2009, it had been announced that Vista usage had surpassed Microsoft's pre-launch two-year-out expectations of achieving 200 million users. At the release of Windows 7 (October 2009), Windows Vista (with approximately 400 million Internet users) was the second most widely used operating system on the Internet with an approximately 19% market share, the most widely used being Windows XP with an approximately 63% market share. In May 2010, Windows Vista's market share had an estimated range from 15% to 26%. On October 22, 2010, Microsoft ceased sales of retail copies of Windows Vista, and the OEM sales for
Windows Vista editions a full installation of Windows Vista through Upgrade media by bypassing the prompt to enter a license during setup, and then, once installed, reinstall the operating system over the previous installation—this essentially allows users who purchased the Upgrade version to perform a full retail installation. While the workaround is indeed possible, Microsoft has cautioned that users who perform a full installation of the operating system through this method without a genuine license for a previous version would be in violation of the Windows Vista end-user license agreement. Users can upgrade from Windows XP to Windows Vista, or upgrade from one