

Specifically, these downgrade rights lets owners of some versions of Vista replace it with Windows XP without having to pay for another license. Downgrade doesn't mean the process for rolling back Windows from Vista to XP, since there isn't such a procedure, not in the generally accepted use of "upgrade." In an older-to-newer move, developers usually make it possible to retain all the digital detritus on the drive, from already-installed applications and Word documents to iTunes tracks and family photos, while updating the system files. To Microsoft, "downgrade" describes the licensing rights it grants to older operating systems.
