How do I turn on automatic updates for Windows Vista?

1. Go to Start > Control Panel. Click on the Security icon, which is indicated by the multi-colored shield.
   
2. Click on the Turn automatic updating on or off.
   
3. Here you are given a number of options for configuring the way Windows updates. Your best option is the recommended option of checking at regular intervals for updates and installing them automatically. Generally Microsoft will release security updates once a month, but sometimes, if there's a severe vulnerability, an update will be released out of the normal cycle. In addition, Microsoft uses Windows Update to provide updates for things like Windows Defender. As a result, Windows Update will likely download and install updates every few days. Checking for updates doesn't require you to do anything and won't slow down your computer, so you should schedule Windows to check for updates daily. Pick a time when your computer is most likely to be on and connected to the internet, and click Ok.
   

If you've configured updates to automatically download and install, an icon will appear in the system tray while updates are downloading and installing.

If you've set up your computer to download the updates and let you install them when you choose, you'll have to click this icon to initiate the update. This process happens entirely in the background, meaning that you don't have to do a thing while this happens. You can click on the icon at any time to check on its progress. Once your computer is updated, a window will pop up informing you that you are now up to date.

Some updates require your computer to reboot, in which case you should save any work you're doing and click the Restart now button in the bottom corner. If this button isn't there, or if you don't want to restart quite yet, click Close. If you need to restart and choose to wait, the shield icon will stay in the system tray, and every few minutes a window will pop up reminding you to restart. You can put off the restart as long as you like, but it's best to do it right after you've installed the updates. You can click on the update logo once you're ready to restart to bring up this window.