The much anticipated release of Vista SP1 is slated for release today, and while many are waiting for that to pop up as an optional download on Windows Update, the full standalone installer is now available for 32-bit and 64-bit editions of the OS.
As usual Microsoft recommends that if you are only installing the Service Pack in one system, you use Windows Update which will result in a much smaller download (the standalone package contains five languages), but knowing our audience it's safe to assume you are better off downloading this one package so you can save it for future reinstalls, slipstream it, or just update the multiple machines you own, and could surprisingly all be running Vista. I don't think the SP needs any further introduction, so just go grab your copy while download speeds are still fast. Release notes are also available on the links above.