Real World Mac Maintenance and Backups

In this book youll find the answers to questions like these When is my Maclikely to have trouble? How can I find out which unnecessary files are takingup space ... » 

In this book youll find the answers to questions like these When is my Maclikely to have trouble? How can I find out which unnecessary files are takingup space on my disk? Should I defragment my hard disk and repair permissionsregularly? What is the best backup software and hardware? How can I make sure Ican restore from my backups? «