License system for Vista

How will work license system in Windovs Vista? On older systems we were used to install system at one computer and use it. That if needed uninstall on that first, and install them to another. But this should change. Vista will be installed from original dvd only twice, and after that it should be useless. It is nonsense, when whole system have to be reinstalled after all hardware changes, after virus affection, after year at most? Seems Microsoft thinks all will be ok, and people will pay more and more.