Excel for Dummies? Sure - there are people who are not computer-savvy for whom an introductory text is appropriate. But these? These are titles in the "For Dummies" series of technical manuals that should NOT HAVE BEEN WRITTEN, because these are things you simply DO NOT LET STUPID PEOPLE DO. Some of these books are already in second edition, those poor bastards.

Biometrics For Dummies
Cryptography For Dummies
Firewalls For Dummies, 2nd Edition
Hacking For Dummies, 2nd Edition
Windows 2000 Server Security For Dummies

These titles seem to work, in sort of a "Modest Proposal" kind of way:

Computer Viruses For Dummies
Rootkits For Dummies