In Windows, how can I tell which service packs are installed?

To determine which service packs are installed on your computer running Windows 2000, XP, or Vista, do one of the following:

• On the desktop or from the Start menu, right-click Computer or My Computer. From the menu that appears, select Properties, and you should see the version number along with other information about your computer.
  
  
• Alternatively, from the Start menu, select either Control Panel, or Settings and then Control Panel. Double-click System, and you will see the system properties.
  
  
• From the Start menu, select Run (in Vista, the second click is not needed). Enter winver . The resulting window lists the build number of your operating system, as well as the service pack version number.

Note: If you don't have any service packs installed, your version of Windows will be displayed without any additional version information.

Also see:

• Best practices for computer security
• What is the Windows Automatic Updates feature and how do I use it?