Many laptops have a Fn button. Fn+Esc on most Inspirons is Stand By or Sleep. If you are lacking the Fn button, there is nothing that I am aware of that will do that. But there is the quick key sequence that should suffice; Windows, s, enter on Vista, and probably the same on most other windows OS's. When I said Windows button, that means the button that brings up the start menu and probably has the windows logo on it.
