Vibration can cause read/write failures increasing latency.
http://www.youtube.com/watch?v=tDacjrSCeq4
However, I suspect the vibrations you're complaining about from a dyer are too low frequency to cause these types of errors. The movement will increase stress on the bearings - a platter spinning at 7200 rpm has a lot of angular momentum, and offers a lot of resistance to being moved. All that resistance is directed at the bearings, and will probably cause them to wear out prematurely.
Rather than try to isolate the drives, I'd try to isolate the case to take advantage of the additional mass of the entire computer. A loosely folded blanket underneath the computer should decouple it enough from the floor's vibration to eliminate the worst of the stresses from the vibration. That's what they do with new skyscrapers built in earthquake-prone areas.
http://en.wikipedia.org/wiki/Base_isolation
http://www.youtube.com/watch?v=YF708pQwAFU