I know there are some people that have a problem hitting the Windows key when in the middle of a game causing the game to exit and extreme noob pwnage commences.  You can disable that key with a little registry edit.
This page explains it
http://www.helpwithwindows.com/WindowsXP/tune-151.html
Or... I played with it and tested it and exported the registry keys so you could have a file to double click on to disable and enable the windows key.  The only caveat is that you need to log off of your windows user account and then back on for this registry change to take effect.
http://videosean.gotgeeks.com/i/WinXP/WindowsKey/WindowskeyDisable.reg
http://videosean.gotgeeks.com/i/WinXP/WindowsKey/WindowskeyEnable.reg
My Enable.reg file just deletes the data in the 'Scancode Map' key.  Use at your own risk, but I'm not keeping the blank registry key in my registry... I don't have a huge problem avoiding the Windows key :P