Sorry guys...I'm going for a serious answer now....
Hard drives will last all different amounts of time. Since there are so many moving parts inside, it's hard to say exactly how long it will last. A good thing to compare it with is the engine in your car. You know it's running smoothly now, but who knows...tomorrow you may start your car and the timing belt may break causing the engine to crawl to a stop (damaging everything on its way to that stop). So we can't say exactly how long. I've seen some hard drives that are 15 years and older, they're just not worth anything because they're 10meg drives. Just remember, if you start to hear loud popping sounds, that's the most common sound when a drive fails. I usually descibe it as "popping", "clicking", or the sound of dropping ballbearings on concrete. I hope that helps.