I have always feared subwoofers wrecking my hard drive, or at least corrupting data.
Even my bookshelf speakers are kept off the desk to minimize vibrations.
I've run systems with sub woofers in them (some pretty large) for about 11 years and never had a hard drive failure in that time.
At the moment i have a set of soundsticks (currently hooked up to my PC) - they do sound good for the price and look great.