Software Backups

What Mac OSX Backup Software should I buy?

I need a backup software program that can back up all my external hard drives and something has features like it only adds data that isn't on the drive you are backing up to instead of overwriting, or something that adds the latest updates you do do files to your external hard drive. Time machine is only good for my operating system computer but not externals. Can anybody recommend any programs out there?

Public Comments

1. read this first: http://blog.plasticsfuture.org/2006/04/23/mac-backup-software-harmful/