Narf, check this web site out --  
{web page}. It lists several other services in WinXP and what they do.  Back in my XP days, I shut down a lot of them, and really sped up my computer during runtime, booting, and connecting to the 'net.  You should go slow, justa few changes at a time, as wierd things can happen when you shut down some.  Also Win XP is stubborn, and restarts some even if you shut them off, unless you reboot immediately.  And do a Google search for more of these sites, there's a lot of info on services out there.