Windows XP has a poor, if not basic, CD Burning Wizard, but is unable, among other things, to burn an ISO image. ISO Recorder is an extension for windows to fix that inability, adding native ISO burning support to the OS. If you're running SP2 the extension adds ISO image creating option and in Vista it adds the function to burn ISO on DVD's. ISO Recorders author also created a tool, CreateCD, to allow CD's to be burned from the command line. Both are free.