Click Start button in the left lower corner of your desktop.
Click My Computer.
Click on the Control Panel link on the left side of the screen.
Find and click on the System icon.
It pops up a new window showing the System Properties. The operating system of this computer is Windows XP.
There is another way to check the Operating System version. Right click on the My Computer icon on your desktop, then click Properties.
It pops up the same window showing the System Properties.