Startup Control Panel, freeware from Mike Lin, is an excellent means of temporarily or permanently enabling / disabling / deleting non-service startup items in NT 4 or W2K. It's a lot more elegant and convenient that using the registry editor. And, as has been mentioned already, the Services applet in the Administrative Tools group is the central way to control the starting conditions for services. However, it's not a good idea to go in there and just start turning services off. Learn what a service is and what it does before you turn it off. And, in any case, it's usually better to just set it to manual rather than to disable it. Sometimes you'll have a hard time re-enabling a service that has been disabled, but re-enabling one that has merely been set to manual works easily.
Hope this helps.
BTW, why have you installed W2K so many times? Problems, multiple machines, or just practice?
Regards,
Jim