From Microsoft:
“We know that many of you are anxious to get your hands on the Windows Vista Service Pack 1 RTM bits. And to that end, we have some good news. We are pleased to announce that–while broad RTW availability is still scheduled for March–the SP1 Update RTM bits are available now to TechNet subscribers. If you are subscriber, please visit TechNet Plus Subscriptions and sign in to access Top Subscriber Downloads. If you have a prior version of the SP1 beta installed, you must uninstall it prior to installing the final version. Check out Things to know before you download Windows Vista SP1 for more information, and for updated details on all aspects of Windows Vista SP1, stop by the Windows Vista TechCenter. “