If you do anything creative involving a computer, make sure you back up your hard drives!
It is not a question of if your hard drive will die, or if your computer will get stolen, or if you will spill that coffee all over your laptop. It is a question of when.
I know a bunch of creative people who have had computers stolen recently. Sure, it sucks to get your stuff ripped off - but it would suck a lot less if you had backups! The real value of the computer isn't the hardware, which can run you a few thousand dollars. The real value is the intellectual property - your photos or music or writing. The stuff you spend hours every day perfecting.
It doesn't matter how careful you are - the technology used in making modern hard drives means that eventually, your drive will cease to function. Even if you don't drop it or drown it or overheat it, one day you're going to boot up your computer and nothing will happen - if you don't have backups, you're going to be screwed.
I'm super paranoid about this - so I have redundant backups like crazy. I go through hard drives faster than nascar drivers go through tires. I currently utilize over 6 TB of storage for my backups. It comes out to about 7 full backups of all my photos. I carry a 16gb flash drive with me around my neck so that even if all my other backups die, I've got my photography portfolios.
At minimum, I suggest you have two backups of your important stuff. Music, photos and documents. Keep one backup next to your computer. Keep the other backup in your office at work, at a friend's house or in a safe deposit box. This way, if your house is subject to a fire or flood - your other backup might survive. Switch out your off-site with your on-site backup every couple weeks, or after a big project.
Hard drives are cheap and they're getting cheaper. I saw a BestBuy ad selling a 1tb external drive for $79 - you can get them even cheaper at places like TigerDirect and Newegg.
Surely your photos, music, documents etc are worth more than $79 to you, right?