The easiest way to get headings of funny `sections' such as
prefaces in the table of contents is to use the
counter secnumdepth described in Appendix C of the LaTeX
manual. For example:
\setcounter{secnumdepth}{-1}
\chapter{Preface}
Of course, you have to set secnumdepth back to its usual value
(which is 2 in the standard styles) before you do
any `section' which you want to be numbered.
Similar settings are made automatically in the LaTeX book class by
the \frontmatter and \backmatter commands.
This is why it works.
\chapter without the star does
.toc file;
secnumdepth counter is greater than or equal to zero,
increase the counter for the chapter and write it out.