Did it come with a user's manual? Have you asked Dell? Not that we don't want to help, but you might try the obvious first.
Just bought Dell Inspirion and I want the option to turn on and off the screen with a button, so that the screen wont turn on before the button is pressed again (even if i move the mouse or push a key). I had this option on my last Asus, it was fn+F8 i think. Is it possible to add this to my Dell somehoh?