Everyone should backup their sites regularly! It's quick and easy and will give you peace of mind. Login into cPanel (www.yourdomain.com/securecontrolpanel) and follow this instructional video.
Then keep your files in a safe place. You should keep your files in several places just in case. (Home, Work and somewhere offsite)
Mozy is a great tool that will automatically encrypt and backup your files off of your hard drive. It's free and really easy to use. The free account comes with 2GB of space! Also check out the referral program. The more people you get to sign up, the more space you get. (If you feel so inclined, you can sign up with my referral ID, M3AH46 and you will get an extra 256mb! )