how do you remove programs that run when starting up?

Hey I have a question.  My computer was taking way too long to start up.  Whenever I turned on my computer like 25 programs started up and ran most of which I didn't need.  I was actually talking with a tech support agent from Symantec anti-virus and she showed me how to deselect the programs from running at start-up that I didn't need.  Now I don't remember how to do it.  I believe it starts by clicking "Start".  Does anybody know how to do this?  I have Windows XP.