Microsoft's latest operating system was introduced to the general public on January 30, 2007. Microsoft applauded the high rate of adoption revealing that at the end of the first 100 days of availability, Vista had sold approximately 40 million licenses worldwide. As of June 2007, according to statistics provided by market Share by Net Applications, Windows Vista accounted for no less than 4.52% of the operating system market, with an installed base larger than Linux and Mac OS X Tiger. Vista's growth comes in the detriment of XP's market share. Windows XP has dropped to 81.94% of the market in the context of Vista.

With XP "expired", Microsoft has even more reasons to support the migration to Vista. The Redmond company provides a comprehensive line-up of offerings to enable XP to Vista upgrades. And one of the latest resources is "Supported upgrade pathways to install Windows Vista", a live webcast event focused on the Office 2007 System as well as 32-bit and 64-bit Windows Vista (sign up via the link). "This Windows Vista WebCast will look at the supported upgrade pathways in Microsoft Windows Vista. The WebCast will include an upgrade matrix that defines the differences between an upgrade installation and a clean installation. This session will cover both 32-bit and 64-bit upgrade pathways," reads the synopsis of the webcast.

Essentially, end users should keep in mind that they will be able to upgrade (or perform an in place install) from Windows XP Home to Vista Home Basic, Home Premium, Business and Ultimate. From Windows XP Professional users can migrate to Business and Ultimate editions of Vista, while Windows XP Media Center can be upgraded to Vista Home Premium and Ultimate, and Windows XP Tablet PC to Vista Business and Ultimate. All the other scenarios of moving from XP to Windows Vista require a clean install.

Microsoft also offers support for moving among Vista editions. Vista Home Basic can upgrade to Vista Premium, Business and Ultimate. But upgrades are more restrictive with other editions of the operating system. Migration between 32-bit and 64-bit versions of the platform can be done exclusively via clean install. In addition, Vista Home Premium and Business can only upgrade to Ultimate. And as far as moving from 64-bit Vista to 64-bit Vista goes, Home Basic can be moved to Home Premium and Ultimate, while Home Premium and Business will upgrade only to the Ultimate edition.