I'm a sys admin and I can tell you most drives die in servers due to use and heat. My maxtor 60gig drive in my car lasted 3 years in a car (off roading every now and then) till i took it out.
It was just mounted normally to the case.. nothing special. If you're really worried use a laptop drive. Or somepeople have put rubber washers around it. The problem with a spring like shock system is you can create more shock.. Or if you wrap it something you'll overheat it.