That's right Skip, especially if you use a straight/rigid mount (articulated mounts have a degree of shock absorption inherent in their design). If you hit one of those spine-jarring ruts that leaves your butt stinging, there's a good chance it will kill your hard drive. The hard drive head is thinner than a hair riding on a cushion of air a few microns above the platter which is whipping by at 5400 or 7200 RPM (about 75mph). A hard enough up/down jolt can cause the head to smash into platter, scraping the magnetic coating off the platter and destroying the head (called appropriately a "head crash"). In this type of crash, due to the physical damage to the platter, chances of data recovery, even by a professional DR company, is slim to none.
So the key is to make sure you have shock protection in the mount itself. Rigid/straight mounts are the worst because they are solidly bolted to the chassis, and any shock is transmitted directly into the laptop. In articulated mounts, each joint dissipates some of the force, so the hard drive stands a better chance the more joints your mount has. I would even go so far as to use a shock absorbing gel (think Dr Scholl's 'gellin') or memory foam pad between the laptop feet and the stand.
But definitely keep a running backup (at least once a week, and any time you add something), preferably a clone with incremental updates via a program like Norton Ghost. Then all you have to do is dump the image to a new hard drive and keep on going.
