You can send and receive personal e-mail, calculate your finances and generally have a blast without doing anything remotely related to work. These aren't exactly the societal benefits that everybody from the computer revolution expected but they're not bad either. You're not a loafer, you're a self-starter. Offer to show your boss what you learned. That will make your boss scurry away like a frightened salamander.
Top management can get away with a clean desk.
For the rest of us, it looks like you're not working hard enough. Build huge piles of documents around your workspace. Pile them high and wide. Never answer your phone if you have voice mail. That's no way to live.