My objection to the mouse-over idea is that many times I have experienced the joy of trying to open programs from the start menu. I click, hover over folder, then onto another folder, then move my mouse wrong and oops, the folder I wanted went away and I have to try again. That's irritating enough when I'm only trying to open a program once every 10 minutes or so, never mind having 6 or 7 chances to screw up the mouse-over per minute.
