1. Its only Available in 5 languages. English, French, German, Spanish, and Japanese.
2. The download size from windows update is much smaller than The Microsoft Download centre.125Mb and 745Mb respectfully.
3. If you have a PC with "problematic " drivers (such as a dell Inspiron) forget it. Come back when you sort it out.
4. If you have a prior version of the Windows Vista SP1 beta installed, you must uninstall it prior to installing the final version
5. If you choose to install Windows Vista SP1 via the standalone installer available on the Microsoft Download Centre, Microsoft advises that you first visit Windows Update and install all optional drivers.

Download Vista SP1 Here

Courtesy of MicrosoftTechnet.