Computers running Windows Vista or Windows 7, by default generate random IPv6 Interface IDs for public and link-local addresses, rather than the EUI-64 based Interface IDs.
I think this is good from a security/privacy standpoint, but from an admin standpoint I feel more at home knowing that the Interface ID comes from the BIA (burned in address).
To disable the random generation and revert back to EUI-64 you can run this as administrator:
netsh interface ipv6 set global randomizeidentifiers=disabled
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