U.S.: Computer query

Anybody have any idea how I can back up my computer files? Normally, I'd burn everything to CD, but the hard disk problem makes burning anything impossible. Here's what the HD problem looks like: HD space reading begins at the actual figure and the amount of free space gradually decreases. Any suggestions? If the suggestion is a new computer, I'll go to Apple's online store, choose one, and wait for you to send it to me.

Anyway, any help with this problem is welcome. I've never had this kind of HD problem before.