Am I running Windows or Mac OS?

If there is a Apple logo in the upper-left corner of your screen, you are running Mac OS. If there is a Windows logo in the bottom-left corner of your screen (followed by 'start' on XP), you're running Windows.

Mac OS X	Windows XP	Windows 7

What version of Windows am I running?

Most likely, it's Windows XP, Windows Vista, or Windows 7.

1. Open your Start menu (click the button labeled 'start' or the orb with a Windows logo in the bottom-left corner of your screen).
2. Navigate to the Control Panel. If the Control Panel not listed on your Start menu, go to 'My Computer' and click 'Control Panel.'
3. Find the ' System' icon.  If your Control Panel is organized by category, it may help to switch to an icon view or 'classic view.'
4. Your operating system should be stated in the System panel.  It may be under the heading 'Windows Edition,' or, if your System panel has tabs at the top, click 'Hardware.' You should find the name under that.

What version of Mac OS am I running?

1. Open the Apple menu in the top-left corner and select ' About this Mac.'

   

2. The version you are running will appear in the window under the words "Mac OS X."  

Note: You can find what major release name your version number corresponds to at  http://en.wikipedia.org/wiki/Mac_OS_X#Versions.