and I'm seriously worried?

Could it be the cooling fan?

Just think of all the slightly less than witty wittisisms you will all be missing if my computer breaks down!

Well, there aren't too many moving parts in a computer. The hard drive moves, the floppy drive moves, and the cooling fan moves. If your computer makes weird noises when all drives are idle, I'd say it's the cooling fan. Electronic components which don't move can whine, of course. There's just no way I could help you without being in the same room as your computer, and I'm not an expert on such things anyway. Probably you should take the computer in to have it checked by someone who makes a living on listening to whines and moans.

Maybe a whore house. Ask for "Priscilla".