Advice about Backup Software.

I'm looking for some decent backup software to use at work. I've heard about the usual recommendations: SuperDuper, Carbon Copy Cloner, and SilverKeeper.

However what I really need is incremental updates (only backing up the stuff thats changed), over two folders. Let me explain that: Were running 10.2.8 server, and from September I shall be splitting the Users folder over two internal hard drives. We have one giant external backup drive which I want to use each night to make a backup of students work. Most applications seem to support only copying new and modified files, but do they support more than one folder to copy?

Any advice would be appreciated. I cant imagine full manual backups each night does the external drive any good.