The product team decided to give you TechNet and MSDN subscribers a little Valentine's Day gift by making Windows Vista SP1 available for download. Go to the http://technet.microsoft.com/subscriptions/default.aspx page. Notice the "Top Subscriber Downloads" section.
And if you're a subscriber, it will require you to log-in with the Windows Live ID you associated your subscription with.
If you're NOT a TechNet Subscriber, I can save you $100 if you're interested.
Source:→ Kevin Remde's IT Pro WebLog
Microsoft, Valentine’s Day, Windows Vista, Service Pack, SP1, Vista SP1, TechNet, MSDN, Subscriber, Gift, Download