I agree with the previous posters...
Yes, you *need* to keep up with the happenings of the W3C org.
My bible is O'Reilly's, "HTML and XHTML: The Definitive Guide". Don't muck about, get this book! Seriously.
Danny Goodman's "Dynamic HTML" book is good too, but it's getting a little dated.
I also highly recommend O'Reilly's "Cascading Style Sheets" book, by Eric Meyer. It rocks my world.
The sad thing is, "correct" HTML doesn't always work... the major browsers don't adhere to the standards set by the W3C, so it's a lot of trial and error to keep up with all of the bugs, documented, and otherwise. You should also check out the developer areas at Netscape and Microsoft.
[This message has been edited by daimoni (edited 05-26-2001).]