Microsoft has begun pushing Vista Service Pack 1 out through the Windows Update service. If you have automatic updates turned on, you’ll get an alert that an update is ready to be installed; when you check, it will be Vista Service Pack 1.
My installations of SP1 have been taking 30-45 minutes, with several automatic restarts. You cannot use your computer while it’s being installed. There are a couple of opportunities to cancel the installation if it isn’t a good time to stop work.
You also may not get that update alert for weeks or months! The rollout will be gradual – not all Vista users will be offered the service pack tomorrow.
Microsoft has identified several pieces of hardware that don’t work after the service pack and is taking steps to make sure that doesn’t cause problems. The manufacturers are writing new drivers now; in the meantime, if you’ve got any of that hardware, you won’t be offered SP1 until after the new drivers have been pushed out through the Windows Update system and installed on your computer.
You don’t have to do anything, just don’t worry if the service pack doesn’t turn up right away.