Agghh! I'm reading about another hard drive that failed and the person did not have an adequate back-up system in place. She saved her photos (Yay!) but lost all of her digital scrapping kits. (Boo!) Recently, several major shops have changed their policies so you must pay a fee to recover digital purchases lost in a computer failure, if they support recovery at all.
It's a matter of personal choice as to how much effort you want to put into backing up your data. Most of the time, people move their data to a new computer before the drive on the old machine fails. But that is no promise that a drive will not fail before you move to a new machine. A backup made today is a million times more useful than a backup you have not made yet, even if you never need it.