And then store each complete set in a separate safety deposit box in a different city, preferably a different state.
Seriously though, how much data are we talking about here? If it's a lot, like I have (over 1TB), there's no way I'm burning it all to DVD. I tend to think multiple HD backup is the way to go, and heck even forget all the RAR'ing, PAR'ing, etc. which in itself will be a problem even for 100's of GB, let alone over a terabyte. Just get 3 HDs big enough to hold it all and copy the data to all 3. Put one in a safety deposit box (seriously), maybe give one to a friend. Encyrypt it if it's sensitive data.