musicandstamps

I have a legal version of windows xp professional and have for the first time encountered the message that the number of times the CD key can be used has been exceeded after upgrading my mother board. I activated windows through the telephone all ok. This worries me however. XP does everything I want so I have no need to downgrade to Vista. So for how long will Microsoft keep supplying activation codes over the telephone? I note that nowhere on the box does it state that reactivation will be an ongoing requirement or that the software is time limited.