Do your normal backups on their regular schedule. This HOWTO is useless if you don't do that.
Build yourself a rescue disk. I now use Knoppix. See the notes on Knoppix below. However, Knoppix has a problem: no LVM support. If you want to recover logical volumes, get a distribution that supports them. For this I use finnix.
In the past, I have used tomsrtbt. It is well documented and packs a lot of useful tools onto one floppy diskette. Unfortunately, the changes I've had to make in the scripts to handle more recent Linux systems cause problems for tomsrtbt. The tomsrtbt 2.0.103 tar is based on busybox, so remarks about it may apply to other Linux disties which use busybox.
We will call whatever Linux you use the "restoration Linux".
Next, figure out how to do the operating system backup you will need so that you can restore your normal backup. I followed Preston's advice and used an Iomega parallel port ZIP drive. The drives get approximately 90 MB of useful storage to a disk. I need about 85 MB to back up my desktop, so a 100MB ZIP drive may be pushing your luck.
Installing the ZIP drive is covered in the ZIP Drive HOWTO, available at the Linux Documentation Project and at its home page, http://www.njtcom.com/dansie/zip-drive.html.