Clone, synchronize, backup. Schedule and forget it. Try it 'til you trust it. Bombich Software's Carbon Copy Cloner is a free download. Version 3 supports Tiger and Leopard.
Carbon Copy Cloner Features:
√ Complete, bootable backups
√ Simple interface for indicating exactly what you want to back up
√ Restore using the same process used for backup
√ Backups are non-proprietary, so you can browse them or use them with Migration Assistant
√ Fast, incremental backups copy only the items that have changed since the last backup
√ Archival backup archives items that have been deleted from the source
√ Support for block-level disk-to-disk clones
√ Support for backing up across the network to another Macintosh
√ Back up to hard drives or to disk images
√ Schedule backup tasks on an hourly, daily, weekly, or monthly basis, or you can indicate that a backup task should run when the backup device is attached (e.g. an iPod). You don't even need to be logged in for your backups to occur!
√ CCC recognizes iPods specifically, allowing time for the iPod:iTunes synchronization to complete
√ Built-in software update feature notifies you when updates are available
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source: http://www.bombich.com/software/ccc.html
Download: http://www.bombich.com/software/download_ccc.php