I have to say, I've been guilty of calling it what it is not as well. I chalk it up to habit - the Windows Command Prompt looks a LOT and acts a LOT like MS-DOS did.
But it's not DOS.
The Command Prompt is just a command line interpreter program - an application in and of itself. It's available in all Windows versions since NT - including the popular Windows XP, Windows Vista, and even Windows 7.
Windows does not operate within MS-DOS because MS-DOS no longer exists in these versions of Windows.
So there's my Monday rant! You can read more about Command Prompt here.