Just consider your own circumstance:
If the best you have now is a flawlesslyrunning Mac, BACKiTUP now!
With a TrustWorthy BackUp when our install sours we simply Erase the Volume/Partition or Initialize the hard drive and Restore it to a known, 100percent TrustWorthy state (and get right back to work on a completely tuned install).
These days I only used Carbon Copy Cloner CCC for backing up my boot working system and applications. CCC has worked so flawlessly for me that I haven't tried other backup options under OS X, including Super Duper application (that many people recommend on the Apple forums) and Apple's own Time Machine.app that is included with Leopard 10.5x.
See link for more detailed information about cloning and restoring hard drives under 10.4 10.5 Leopard OS X.
by: ©2003 G. BALLARD www.gballard.net
Note: G. BALLARD prefers a shredding if he is wrong or unclear.