What is your disaster recovery plan?
I remember asking a good friend a few years ago who shoots weddings and other events, how he backs up his data. He explained how he has multiple external backup drives in the event that his computer's hard drive crashes. That's a good start, but what happens if you're hit by a fire or all of your drives and computers are stolen in the night. That client that wants to finally put her wedding album together isn't going to be very understanding when you say you don't have any pictures.
Currently when I import images from my camera onto my computer, they are stored on 2 drives that are configured in a RAID 1 configuration, i.e. a mirror image of each other. Then, I push them over the internet to a shared NAS drive at a friends house on the other side of the country. If I lose a hard drive locally I'm ok. If my house burns down I have backups I can reach remotely.
I also NEVER change any of the original files. The original RAW file or JPG is never altered in any way shape or form. Using Adobe's Lightroom I manage all of the changes within that application and also back up the Lightroom Database to ensure that I have those changes in the future.
Chase Jarvis explains his process. It makes my process look like preschool, but at the end of the day I'm covered from multiple angles. If photography or video is how you pay your rent, you might want to step it up a notch. The great thing is that you can do it all fairly inexpensively.