In reply to Ice Nine:
Not particularly great solution here, but better than nothing. In short the more important the data, the more copies and the wider they are spread.
In our case:
Primary Storage - PC Drive 1
Secondary Storage - RAID Array on Server - stuff copied there once a month or so.
Tertiary Starage - External Hard Drive, stuff copied once every month or so.
I am painfully aware that all of these are on one site, in fact they are all within 10ft of eachother.
I do have off-site storage for some data, but not all by any means.
I did wonder about doing a deal with the neighbour and him putting a server in my basement, me doing the same with his, and running a cat5 pipe between them across the ground between the buildings, and backing up there.