If you're talking about keeping some programs from starting at startup, then do this:

Go to Start, then Run. Type "msconfig". Go to Startup and do one of the following:

If you use Windows XP then uncheck ALL the boxes.

If you use anything other then uncheck all the boxes EXCEPT rundll or something like that and systray.

That always works and makes my computer feel "clean" from those damn fagz0r progs that startup when you start your comp.