Hi Anhaedra,
as bloodline said, there's a TV-out plug on the back which you can hookup to any TV (or VCR) which takes a composite input and see if anything comes up. Even without mouse and keyboard, it should still show the boot up screen (if there's not hard drive).
Now the easiest way to find if there's a hard drive is to take out the 4 screws on the side and the one in the back and remove the cover. Simple.
