We have always had a problem with backing up our files.   Not that we forget to do it but because of the expense and the space it takes.  We have gone from floppy disks to cassettes, to CDs, to DVDs,  and our latest is portable hard drives.   With 50 GB of portable storage in our home you would not think we would need any more.  And size wise we do not.  But for safety we have decided to go with online backup storage.  I have no guarantee that my portable hard drive will not crash or disappear at the same time my computer goes out on me.