From InfoWeek:
When Windows Vista is available, consumers will be able to transfer the OS license they purchase to only one machine other than the one for which they originally buy Vista, said Shanen Boettcher, a Windows general manager at Microsoft. He said Microsoft thought the change made sense because "lifetimes for PCs are getting longer." Most likely, a user will not need to transfer an OS license to more than one computer during the time that OS is the latest one available, Boettcher said. "It's a fit for what most customers do," he said. Boettcher added that XP did not have a specific limit for the number of times the license was transferable, but that Microsoft wanted to be "specific" about transfer rights with Vista.
When Windows Vista is available, consumers will be able to transfer the OS license they purchase to only one machine other than the one for which they originally buy Vista, said Shanen Boettcher, a Windows general manager at Microsoft. He said Microsoft thought the change made sense because "lifetimes for PCs are getting longer." Most likely, a user will not need to transfer an OS license to more than one computer during the time that OS is the latest one available, Boettcher said. "It's a fit for what most customers do," he said. Boettcher added that XP did not have a specific limit for the number of times the license was transferable, but that Microsoft wanted to be "specific" about transfer rights with Vista.