Nah, no need to back up. All my documents and junk are on my PowerMac and I just sync them over to my PowerBook every now and then. If my PowerBook's hard drive craps out, the only things I'll lose that are of importance is a movie I got from questionable sources and a pretty wallpaper I got off Deviant Art
Frankly, I'm kinda hoping the hard drive dies. I do have a good feeling I'd get a replacement laptop this time around
But of course, I won't try to cheat Apple and make the hard drive go quicker or anything, but if it finally dies, I most likely won't be too terribly upset
Anyways, I'm running Apple Hardware Test right now. Doubt it will tell me much, but I've got time to kill.