Yes, but, when your computer is cluttered, the hard drive is accessing data more often than when it's free. I'm sure your external hard drive doesn't get a lot of use compared to your internal, even if you've installed programs onto it. Most external hard drives spin down in about 3 minutes of inactivity. Also, the external hard drives are typically the same as a desktop or laptop hard drive, but they're in cases. Even firewire can't transfer data as fast to your computer as your real hard drive can, let alone USB (which is what most people have). An external hard drive works much less hard than an internal one because of these reasons, and therefore will last much longer than an internal hard drive ever would.
and ticking away just fine.
I hope you're not serious. A ticking hard drive pronounces its imminent death.

It should make a small sound when it's been asleep and you go to access it, but even when you're transferring files to it, it should be silent.