When you Maximize a window in Windows 2000, Windows XP, Windows Server 2003, and greater, the window may NOT be displayed in full screen mode, as the taskbar 'always on top' setting is respected.
If you need maximum display area for a particular window:
1. Open the window normally. If it opens Maximized, press the Maximize button to return it to a normal window.
2. Hold down the CTRL key and double-click the window's title bar.
NOTE: I have found one computer that only works this way for Windows Explorer and Internet Explorer. It respects the 'always on top' setting for other applications?