I am supposed to be transitioning to using Linux for work, starting with Ubuntu. I was told that when I have a laptop with Linux I should not move it while it is operating before I make sure disc protection is enabled in Linux. Is this true? This is scary. Can I damage my disc so easily?
Most harddrives are designed, from the factory, to handle a fall from a certain height and still survive without data loss (shock resistance). This is usually specified on the hard drive's sticky label. Not sure how many Gs this is, but I would guess they should be able to survive a 2-3 foot fall onto carpet, say from a coffee table. (If anyone knows better about this, like say from a purchasing group, please comment on this and I'll add the info to my answer). Falls from say a boardroom table, I suspect, would really start to push it. Of course, there are no guarantees here. But most hard-drives are designed to take a bit of a beating.
When on, however, a drive's ability to survive a fall drops significantly. Some laptops (notably ThinkPads) include accelerometers that can detect if your laptop is tipping or being jostled, and will turn off the drive if the software that governs that behavior is loaded, with the goal of improving data integrity. I'm certain you can get an app for Ubuntu to do this too. Mainly the turn-off feature is useful when using your laptop in a bumpy environment, say on a bus or train, or in the back of an automobile, to limit the possibility of a head crash occuring. No amount of software can prevent physical damage to your disk from a major fall, though. If your'e going to be moving your laptop around a lot, it's definitely something you'll want to have active.
As always - just be careful, don't let your kids attack your laptop, and try to limit the drops it makes to the floor as much as possible. If you ride the bus/train/carpool and use your laptop during those rides, I'd try to get a jostle-detection tool on your laptop, assuming it has the appropriate hardware. It's not the end of the world if it doesn't, though, as many other posters have noted.
I have dropped my laptops (cheapo Acers and a Lenovo) many times over the years sometimes while booted in to Linux sometimes Windows. I also accidentally spilled whole glassfuls of water, soda and hot tea on them.
I only caused irrecovorable errors on a hard drive once through all of this. It was a fall from about 4'6" while I was walking and I was encoding a large AVI file. I tried to catch it in the air and ended up causing the laptop to do a few loops in the air before crashing on to the parquet floor hard.
Even then, I was able to recover most of my files by booting using ArchLinux on a USB key.
In any case, Linux does not cause hard drive damage. However, if you have a lot of processes writing to the disk at the time a physical shock occurs, the number of sectors damaged can be greater, regardless of the OS.
One thing you have to watch out for is your power saving preferences. The laptop mode tools FAQ list addresses such issues:
Spinning down too many times may kill hard drives
Desktop hard drives are usually rated for only 40,000-50,000 spinups, and one spinup every 10 minutes will kill your 40,000-spinup HD in 277 days. So this is NOT recommended for server use, unless you increase the spinup interval dramatically, to say once every hour or two. Laptop hard drives are usually rated for around 300,000 spinups, so those will last about 2083 days or 6 years if you have them powered on 24-7.