Lord: something important to keep in mind (and johnmullen made reference to it) is that a
lot has changed in the world of html in the last few years. Actually it changed a 4 or 5 years ago, there's just sooooo many people out there that persist in doing it the old/wrong way that the problem perpetuates itself.
Specifically, if you're going to start out fresh you might as well save yourself a lot of crap and stick to XHTML + CSS.
Here's a great start:
http://www.w3schools.com/xhtml/xhtml_intro.asp
And (as per my sig) you should eat sleep live and breath
http://validator.w3.org
One handy trick is if you use IE, to add this link as a bookmark in your "Links" toolbar. With it you're only a click away from validating whatever page you're on.
javascript

ocument.location.href = '
http://validator.w3.org/check?uri=' + escape(document.location.href) '&ss=1'
IE will bitch that there's no program for 'javascript' or something, just ignore it.