The Start menu gets more real estate in XP than in previous versions, and it's more customizable. To make the Start menu display only the applications you want, rather than the default determined by M'zoft:
Right-click in an empty section of the Start menu's left column.
Select Properties > Start Menu > Customize. Here you'll find a list of your most frequently used programs. (XP keeps track of what you use and what you don't, then updates this list dynamically).
Don't want your boss to know that Pinball, Solitaire, and Quake all make your list?
Go to the General tab, click Clear List, and set the counter to zero.