For everything in life, there should be some sort of Disaster Management. It is wise to be prepared for any unforeseen event. This also applies to your PC running on Windows XP. There are many reasons why a Windows Operating system may fail. Some of the reasons are corrupt system files, a corrupt Hard Disk, virus, or an unusable system registry.
Be prepared to counter such an event before the disaster strikes and you lose valuable data on your PC. One option available is to backup important data regularly to some remote location. However, to access this backup, you need to be able to turn your PC on (in other words, boot your PC). Until and unless your PC can read a CD/DVD, you cannot access the backups you created.