If you are using windows to write the CD, once you copy the file to the CD, before you eject it you have to write the files to the CD. To do that,
Under CD Writing Tasks, click Write to CD.
After the CD Writing Wizard starts, follow the instructions in the wizard.
When the process is finished, the wizard displays a check box for you to choose to create another CD like the one you just made. If you want to create multiple copies of the same CD, click Yes, write these files to another CD and insert another blank, writable CD into the CD recorder. Follow the instructions in the wizard. NOTE: After you copy files or folders to the CD, it is useful to view the CD to confirm that the files are copied. If you don't want to create another copy of the same CD then click No.
As for taking a while, no worries here. And once you get the data backed up, we can definitely try doing the repair install first. The total reinstall is always the last thing I want to do.