You can download Windows Vista SP1 via Windows Update. For those of you eager to receive the benefits of Windows Vista SP1, you can now do so.
For those of you happy to wait, sit tight because SP1 will start downloading to customers PCs automatically beginning in mid-April (remember, this happens only if you have your Windows Update configured to automatically download updates and SP1 will automatically download but not automatically install). But if you want to get the benefit of a year's worth of improvements right now, go check Windows Update today (hit the Start Menu, All Programs, and select Windows Update).
For the standalone installers:
x86: http://www.microsoft.com/downloads/details.aspx?FamilyID=b0c7136d-5ebb-413b-89c9-cb3d06d12674&DisplayLang=en x64: http://www.microsoft.com/downloads/info.aspx?na=22&p=1&SrcDisplayLang=en&SrcCategoryId=&SrcFamilyId=&u=%2fdownloads%2fdetails.aspx%3fFamilyID%3d874a414b-32b2-41cc-bd8b-d71eda5ec07c%26DisplayLang%3den
A sneak preview of the improvements:
For more info check out these pages: Product Page and Technet