Some facts:
Older hard drives have lower
areal density and bigger, chunkier internal parts. So if a square millimeter of HDD dies on a modern 500GB drive, you lose 100GB. On an older 20GB drive, you only lose 400MB or so (numbers pulled out of the air for illustrative purposes only).
Laptop drives are usually made with systems that try to make sure to slam the read/write head out of the way before any sort of catastrophic impact (See Apple's
SMS technology for one example). Portable drives also usually have fewer platters, lighter components, etc. and so aren't as affected by vibration as larger drives with larger, more massive parts. Because they're designed to be used in portable computers, they also have hardware systems designed to better survive these things (better bushings, etc). This is also one of the reasons they are so much more expensive than equivalent desktop drives.
You
can get desktop drives that are beefed up for rougher and/or heavier use. Look for so-called '
enterprise' or '
RAID-optimized' or 'military grade drives.' Keep in mind that many searches for 'rugged HDD' will end up pointing you to solid state drives.
Any HDD can be made more reliable by keeping it cool, mounting it with bushings to cut down on internal/external vibration, not beating the crap out of it with constant defrags and 24/7 operation, etc. Just remember that, in consumer-level drives, speed/size usually is inversely proportional to reliability.
--Patrick