How to Find Out Which Windows Is on a Computer
- 1). Click on the "Start" menu on the lower left corner of your screen.
- 2). Select "Run."
- 3). Type "winver" in the box, then click "OK." You will see a new box that will tell you which version of Windows you are running. It will also tell you if you have a service pack installed. Service packs are updates to existing operating systems.
Source...