Sue,
Just to be even more .. er..helpful:
Our research and experience with disaster recovery of backup files suggests that CDRs may be more stable that CR-RW (re-writable). Things we're going to back up and squirrel away go to CDs. Things we are going to back up in ongoing or episodic ways go to re-writable media. Being a belt and suspenders guy when it comes to important data, we make and lock away a CD for stuff we never want to loose or change. We use removable HD and DVD-RW for stuff we are backing up all of the time.

Backing up is only 1/2 the problem. To restore, you need to be sure the program or utility you are using is backwards-compatible. You sound like you're using something preXP. Be warned that if you're trying to restore to a new computer (e.g. to recover data after a fire of stolen computer)you'll feel more comfortable if you test your backup on someone's newer operating system.

Forgive me if this is more than you wanted to hear.