How can I tell what operating system am I using?

If you are using Windows:

If you are using a Mac:

• Right click your "Computer" or "My Computer" desktop icon and select Properties.
• Your OS will be displayed on that screen.
  

  Windows 7, Vista, Server 2008/2011

  

  Windows XP, Server 2003

• Click the Apple icon in the top left corner.
• Select the "About This Mac" menu item. Your OS is displayed on the splash screen.
  

  Mac OS X 10.4, 10.5, 10.6 & 10.7