There are a quite a few ways to backup DVD’s and other images using the GUI.  This one produces an identical digital image, including the boot camp partitions on a Snow Leopard DVD, of which I was making a backup copy.

Simple method to copy a data CD or DVD:

1. Open Terminal (Applications>Utilities>Terminal)
2. Check where the disk is mounted:  df
3. Unmount the disk:  umount /dev/disk2s3
4. Copy the disk to a file:  dd if=/dev/disk2s3 of=image-name.iso
5. Burn using Disk Utility

/dev/disk2s3 is the device location df returned for my DVD drive
image-name.iso is the name of the iso image file that will be created.
Resulting image-name.iso is your CD/DVD image.