Most Windows-compatible keyboards include a Windows logo key that can be used to open the Start menu, or can be used in combination with other keys to start certain Windows functions.
The Windows Logo key is generally located left-hand between the "Ctrl" and "Alt" keys and duplicated right-hand of spacebar and right "Alt". Here's a complete list of Windows XP keyboard shortcuts with the logo key.
Windows Logo: Display or hide the Start menu
Windows Logo+TAB: Cycle through taskbar buttons
Windows Logo+Break: System Properties dialog box
Windows Logo+R: Run dialog box
Windows Logo+U: Open Utility Manager
Windows Logo+M: Minimize all
SHIFT+Windows Logo+M: Undo minimize all
Windows Logo+F1: Help
Windows Logo+E: Windows Explorer
Windows Logo+F: Find files or folders
Windows Logo+D: Minimizes all open windows and displays the desktop
CTRL+Windows Logo+F: Find computer
CTRL+Windows Logo+TAB: Moves focus from Start, to the Quick Launch toolbar, to the system tray (use RIGHT ARROW or LEFT ARROW to move focus to items on the Quick Launch toolbar and the system tray)