I'm always surprised that not many people do this. I do a backup every 2 weeks or so.

My most important data is this website, and work-related documents I've collected throughout the years. My computer is 3 1/2 years old now, and sometimes hard drives fail unexpectedly. There's really no reason not to back things up since external drives are so cheap now. Newegg always has great prices:

http://majorindulgence.com/u/39

Better safe than sorry when it comes to these things.

yes, I've had a 500 GB Western Digital External Hard Drive for a little over a year now and back-up everything religiously. Everything I download and everything I save, be it word documents, pictures, game files, music, etc, it all goes on this external hard drive. It makes things a lot easier on you when your computer craps out and you either have to reformat the hard drive and reinstall an OS, or complete scrap the computer and buy a new one. Set up the new computer, plug in your external hard drive, and there's everything you've ever saved or downloaded. It's a simple concept, back-up everything, and you'll rarely lose anything!