My old colleague Remko Lodder about backing up, to DVD:
PEOPLE PLEASE if you have important data that is very valuable for you, be it pictures, music, movies, financial records, please make sure you have a periodic and good backup, test whether it works (You are not willing to find out it does not work when you need the actual data), make sure really important data is not kept at home on one laptop / computer / usb stick, but are spread over multiple locations, burn them on DVD and in case really needed put them in a vault at the bank.
It is often that people realize they need to make backups when it is too late. My tip is always to make backups to two different media in two different places, with minimal one off-site. Remco is focussing on DVD as a backup medium, but I have to point you to the FAQ of Archives.org. The life-span of optical media is 2-5 years, which is a risk for a backup medium, hence the two different media. If you add disk or tape to that and you test them every two years, you are safe.