Well, technically, the OEM Vista EULA has not yet been released, so any
discussion regarding this is strictly conjecture until the OEM EULA is
officially published. Having said that, If system upgrades on a computer
with an OEM version of Vista are significant enough to cause the computer to
look like a new PC, you'll be required to reactivate within 30 days (this
was previously 3 days for XP.) Different components are assigned different
re-activation trigger values, with the motherboard and hard drive housing
the operating system being the highest-weighted components in a system. The
operating system must remain with the system that retains the motherboard.
Per Microsoft, other PC components (such as RAM and hard drive) may be
upgraded without requiring a new operating system license. The operating
system may be installed on a new/replacement hard drive as long as the
operating system is first removed from the old hard drive. Re-activation
policy may be stricter when upgrading a motherboard as opposed to other
components; we'll have to wait and see how Microsoft will train their
telephone activation representatives to handle such re-activation requests
for a system with a different motherboard.
-Russell
http://tastycomputers.com