Gize, gize, gize.....as I recall, the backup in Win98 is a lamed out version of Backup Exec 98 made by Veritas THAT WILL NOT SPAN. Backup Exec by Veritas will allow you to span cd-rw's and maybe cd-r's, as long as your hardware is supported. See their site for supported and tested hardware (burner, tape drive, etc.).
I have used Backup Exec 95 with a tape drive, and Backup Exec 98 with my burner. I presently use Plextor's CDResQ, which is a version of Ghost by Symantec (Norton). This does automatically span cd-rw's. I believe that newer versions of Drive Image by Powerquest and Ghost by Symantec also span images.
Nero Burning Rom also makes images. I believe it spans them, but I am not positive about this.
One hint.....before you make images, I suggest that you stop everything from running, except Explorer and systray. Especially, antivirus programs. I have found from experience, that restoring an image with Norton Antivirus running, can be.....problematic.
Also, your backup is only as good as your ability to restore it. So.....you might want to test a backup every now and then. Maybe restore it to a spare hard drive and see if it works.
--Randy