If you change certain compnents within your pc you will
be asked to reactivate - a hard drive is one such
component that requires a reactivation. You may have to
telephone the toll free number for activation, but you
should have no problems reactivating.
One tip, however, after reading Alisons reply. Never
activate straight away. You have 30 days to activate. Run
your machine for a week or two first to see that xp is
working ok before activating. This will prevent the need
to activate two or three times in one week. This also
applies if you have to reinstall xp.
Hope this helps
John Barnett - MVP
Associate Expert