I use CD-RWs for my backup. They work excellent. They essentially are giant floppy disks. And like floppy disks, over time they can wear out. From what I've heard it takes over a million burns to degrade it enough, so that's not much of a concern.
As for your problem Mat, I think I have had that problem before. The only thing I could recommend is to upgrade to 10.2.4 or better. Not only will it hopefully help with the burning issue, but it'll take care of a disgusting icon problem on the desktop. If you put an icon somewhat off the screen on the left side, it is automatically moved onto the screen and shoves everything else on the desktop to the right. By the third time you place an icon off the screen your hard drive is off the screen. That's at least one good reason to fix. Also, what type of Mac are you using?