Tony -- Windows XP uses NT-type services which are viewable under Control Panel -> Administrative Tools -> Services, and can be started/stopped/disabled from there.
http://www.theeldergeek.com/services_guide.htm has a list of Windows XP services and details on what they do, and how important they are. It's a very good list I use whenever I have a new install of XP to 'slim down' process-wise. Unfortunately the site has exceeded its bandwidth usage limit so is unviewable atm!