[Andy A.]

I'm curious, how were you going to power it?

While hard drives are the most obvious targets of vibration damage, theres more to be worried about.

While most of the PC is solid state, none of it is 'shock/vibration proof'. Everything from the power supply down to the screws holding the motherboard to the case could be damaged from prolonged vibration. R/C plane builders know all about just how damaging vibration can be to even simple solid state electronics, and will wrap receivers in latex foam and servos are often shock mounted. High vibrations can crack solder joints, work heavy capacitors loose, loosen heat sinks, knock a RAM module out etc.

My guess is that even if you don't see a hard drive failure, you will see one somewhere else. I'm sure its possible to do this, and I think it has been. However, the desktop PC wasn't made to move around. And being bolted to a lawn mower is about as terrible environment as I can think of.

My suggestion is to look into buying an old laptop, perhaps a Toughbook. A laptop has been designed to move around and deal with a life of being dropped. You'll still have to do something about vibration, but at least you don't have to worry as much about powering it.

And be careful about advertised 'shock' and 'g loads'. Usually these numbers refer to a devices ability to handle drops when off. A spinning hard drive is much more apt to be damaged then one that is powered down.

-Andy A.