If your intention is to use Apache, then Lauries' book is probably not just definitive, but essential.
Firstly what this book is not; it is not an Apache manual, this can be downloaded from Apache web site (start athttp://www.apache.org/orhttp://www.apache.org.uk/). It is not a book about HTML. Lots of those exist. It is not a book about how the Web works; in fact a lot of assumptions are made in that regard. The reader needs to be well- informed on Web basics. It is not a book on Java or Perl or Web programming languages.
Specifically the Lauries' book is about installing and setting up an Apache Web Server. As the cover states: half the world's Web sites are run on Apache Web servers and this share is rapidly growing. One of the problems faced by the authors is trying to write at a speed that can keep up with the pace of development. Readers need to be aware of this and keep a close eye on the above site for up to the minute documentation.
Apache is just one project in the Apache Software Foundations portfolio, others being Jakarta, Java Apache, Mod Perl and Mod php.
It is free, again downloadable from various mirrors or available on the CD that accompanies this book. I was able to fire up the CD on my Unix box and go through the initial stages of an installation, without too much difficulty. As my server is currently mission- critical I couldn't risk a complete installation, but it all looked fairly civilised to me.
Most of the text assumes a Unix installation and BSD to be precise. It deals with installation out-of-the box and some of the pitfalls of not reading READMEs and it assumes building from source, rather than installing binaries.
As the authors point out, the main problem with Apache under W32 is its security. Security in Apache relies on security in the underlying OS, hence the problem.Unfortunately, Win95 and its successors have no effective security worth mentioning.
I have no reason to doubt its claim as the definitive guide and the 2nd edition is probably justified. If your intention is to use Apache, then Lauries' book is probably not just definitive, but essential. It takes the reader through from the design of the simplest possible 'hello world' site to a complex application involving on-line forms etc.