Actually, shutting down the computer for the computer's health is old advice and doesn't apply any more. And if you put your computer into "sleep" mode, you won't be using anywhere near as much power as you would if you kept it "on," but you can start up faster and your num lock preference would probably hold. I would still power off every now and then, since that will help free up memory that programs hadn't released properly, but you needn't do it every night.
Joy,
Lynn
