I suspect all the stuff we save on our computer is the same as all the physical stuff we store in the attic or the garage. We don't need it and will probably never use it!
When I was getting rid of my first proper computer, I sat for a whole Sunday with a huge box (80 I think) of 3 1/2" floppy disks backing up stuff - all my college projects and other stuff. The computer didn't have a CD drive never mind a CD burner. Those disks are still sitting in a box in my parents attic and I have never once tried to access any of this hugely important data and a) I'm not sure they'd still be readable and b) I no longer own a computer with a drive to read the things anyway!
I tend to upload my digital photos to Flickr and I can download them again any time I want them. I work on the assumption that Yahoo has better backup systems than I have...