Windows 7: Microsoft makes it legal.

For the past few years, Microsoft has been conducting experiments in various countries as to how and whether “renting” software could become a viable business model. The answer seemingly must have been yes, since Microsoft quietly added rental SKUs, as of January 1, to the list of license types available to customers worldwide.
Though some industry watchers consider Microsoft’s various annuity licensing options — like Software Assurance, via which users pay for the right to use Windows, Office, and other Microsoft products, in chunks over a period of three years — to be “rental” programs, they technically aren’t. Under the newly introduced rental program, a customer would pay a flat fee to use Windows or Office 2007 (Standard or Professional versions) for a year.