books

I have the book, "Postgres Introduction and Concepts" by Bruce Momjian
dated 2001 (version 7.0.2) and O'Reilly's "Pracitcal PostgreSQL" dated
2002 (version 7.1.x).

I already noticed a change in the pg_hba.conf files to include an extra
column from the books to my current version 7.4.2

I am trying to assess the need to keep using these books. I am assuming
that probably 90% of the books are valid until I get into vacuum and
some administration goodies.

Without reading all the changelogs yet, am I close?
I know I'll have to keep hitting the docs themselves to be sure, but I
would hate to toss these before they get a chance to get really worn out.