This protection scheme will limit the features of illegal version of Vista. If a legitimate product key is not activated in 30 days, Microsoft Vista will go into reduced functionality mode.
The screen will show a little sign saying "this copy of Windows is not genuine", while Aero won't work and the ability to use a PC will be impaired.
Now we know what you're thinking, but this is what Microsoft means. Vista will let you use a browser but not all the time. Microsoft said: "Windows Vista will have a reduced functionality mode but one that is enhanced."