There are now several online backup services that are offering unlimited amounts of data storage. Backing up to an external hard drive or CD/DVDs is a great first step but you have to make sure you also store copies of your data (yes, all those gigabytes of digital images) off-site, just in case of fire, water damage, lightning, theft, and other stressful things, like hard drive failure. Carbonite offers unlimited backups for $55 a year and gives you the connivence to access any of those files from anywhere in the world through a web browser. Mozy offers backup packages starting at $5 per month.
Remember, its not IF your computer or hard drive will fail, its WHEN. Been there - done that, it is not a good feeling.