I can't figure out how to program the programmable keys on my Dell keyboard. The keyboard model number is SK-8100. I have a Dimension 8100, Windows XP, if that matters. At the top of the keyboard there are three keys numbered 1-3. Key number 1 has an e-mail icon, key number 2 which is larger than the other two has a homepage icon, and key number 3 has a magnification icon. It looks as if these keys should be already programmed, but they don't do anything. Any help would be appreciated!