This is more of a reminder for myself than anything else ….
If you need to reboot a Windows XP machine from DOS prompt the command is:
shutdown -r
If you just use the command:
shutdown
without passing any other parameters to it you’ll get the help screen with a variety of options.
Kind of useful if your PC (located remotely) is acting up and a reboot is required 
From Mark Brislane:
For a nice GUI interface to this, just run :
shutdown /i
From Michele Neylon:
GUI? We don’t need no stinking GUI!!
Thanks for the tip though