Relying on one type of media = mistake
Thinking DVDs are reliable = mistake
You need the 321 rule. 3 copies of everything, on 2 different mediums, and 1 off site.
I would recommend for you getting a drobo
http://www.google.co.uk/products/cat...d=0CDsQ8wIwBA#
You can put 8 TB in that one I think. It is intelligent back up. If one of the 4 HDDs dies, it doesn't matter. You can hot swop it, put new one in and you're all good.
You also need an offsite back up. I use
http://www.carbonite.com/ it works out to 15 cents a day.
I would agree that tape would be better than DVD for your other onsite storage.
So you have your PC with all the content on, backed up to the drobo, and you have DVD/Tape and then carbonite too.
That's what I do anyway.
HTH
Damian