Mac OS X 10.5: When to use Time Machine or .Mac Backup to back up data:
If you have Mac OS X 10.5 Leopard and are a .Mac member, you may be wondering when to use the (.Mac) Backup application or Time Machine to back up your important files and data. The answer depends on which files you will be backing up and where they will be backed up.
Note: You should not back up any data outside of your Home folder with Backup. See this article for more information. Time Machine can easily back up files outside your Home.

Backing up to a network volume, external hard drive, or different disk