if ur running ur system in ur car u dont want to use normal hard drives because rattling them while they are on can destory them... i cant remember were... but i have seen adapters to use laptop drives in regular pcs... u might want to look into it
aha! you all are right. SO with that you turn the HD up on its side(and have shock absorbsion material). the force is directed to the shaft which can handle alot, and if the bump is big enough the only thing that will happen is your computer crashes because it lost its train of thought. Yes it will still torture the drive, but thats wat it gets for being the one chosen for automobile usage.