Well, if your dvd's also destroyed in fire-bad luck. I think you can also transmit the virus on your dvd - so nothing can be immune from that problem.

The best is to also store it in another pc. At my home I have two pc's and I also backup my HD to another pc HD and vice versa over the network line - fast and easy. It does it everynight without me really have to do anything. This is just in case my PC got struck with a lightning which is highly improbable. I also backup to CD for very critical files every month or so.