Anyone make a backup DVD for their Navigation system? I never did any DVD burning but I do have a burner and would like to make a backup...this way I can use the backup and keep the original in a safe place. Can this disc be copied and used? Any tips or pointers to how I go about doing it? I copied the nav disc to my hard drive and it tells me I need a blank disc that has a capacity of at least 14.53 GB.