If and when that terrible day your Mac dies finally catches up to you, you can be back up and running with all your applications, settings and data in under 5 seconds with a bootable system clone. By mirroring your entire Mac's hard drive to an external FireWire drive, you can boot from that disk using any other Mac and have your entire system at your fingertips, no tedious software installations, System Preference setting or desktop wallpaper hunting required. Using the excellent free version of SuperDuper and a regular old FireWire drive, here's how to mirror your Mac onto a bootable disk.
For more on backing up your Mac using this method plus plain old document backup, see Complete, Free Mac Backup. PC users, the process isn't quite as simple for you (with free software, anyway) but here's how to partition and image your hard drive with the System Recovery CD.