I have had a disk head crash before actually. Cartesius over in the C4D forum just had a disk failure, one of my co-workers had one about 2 months ago. You hear of a couple a year in these forums and I have seen a couple outside as well. If your back up HDD dies, no prob, you still have everything on the main disk. If the main dies, you still have your backup files.

My backup contains a clean install image for windows and all main progs, a compressed archive of all my essential downloads (patches/updates and other things that I may not be able to find again easily), my model files and my archival (lossless) full res images. In a way, I am doing a very simple RAID type of setup.

Pass no temptation lightly by, for one never knows when it may pass again!