Here are the Key combos for XP
Windows Logo (Display or hide the Start menu)
Windows Logo+BREAK (Display the System Properties dialog box)
Windows Logo+D (Display the desktop)
Windows Logo+M (Minimize all of the windows)
Windows Logo+SHIFT+M (Restore the minimized windows)
Windows Logo+E (Open My Computer)
Windows Logo+F (Search for a file or a folder)
CTRL+Windows Logo+F (Search for computers)
Windows Logo+F1 (Display Windows Help)
Windows Logo+ L (Lock the keyboard)
Windows Logo+R (Open the Run dialog box)
Windows Logo+U (Open Utility Manager)
Windows Logo+Q (Not sure, but it shows the current users name in the middle of the screen, may be used for quick user switching)
Well, not all of these work in xp, but here's an expanded list
Windows Logo: Start menu
Windows Logo+R: Run dialog box
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)
Windows Logo+TAB: Cycle through taskbar buttons
Windows Logo+Break: System Properties dialog box
Microsoft Natural Keyboard with IntelliType Software Installed
Windows Logo+L: Log off Windows
Windows Logo+P: Starts Print Manager
Windows Logo+C: Opens Control Panel
Windows Logo+V: Starts Clipboard
Windows Logo+K: Opens Keyboard Properties dialog box
Windows Logo+I: Opens Mouse Properties dialog box
Windows Logo+A: Starts Accessibility Options (if installed)
Windows Logo+SPACEBAR: Displays the list of Microsoft IntelliType shortcut keys
Windows Logo+S: Toggles CAPS LOCK on and off
Windows Logo+U: Opens Utility Manager