Originally Posted by Trogon

Same failure rate, it's nothing more than an internal hard drive housed in a box and attached via USB. The things that kill the drive in your computer will kill one of these just the same.

Not saying they aren't a good idea - I have one - just saying for irreplaceable stuff, you need to use a perpetual media. Backing up everything to an external drive is the best way to prepare yourself for a catastrophic failure. You clearly don't need to burn every little thing onto a DVD, though using a disaster recovery program and burning a disk image to DVD once in a while is a good strategy too.

Just don't forget that a random carload of crackheads with burglary in mind won't leave the external drive untouched when they steal your computer. Same thing with a fire that burns up your office. Or any other type of natural disaster. If the computer goes in some physical manner, the external drive is going with it.