Initially, all you had to do to center everything on an HTML page was to use the <center> tag.
With XHTML 1.1, the <center> tag has gone completely! so you'd have to use the <div> tag or a table or something else to center your content!
At the end of the day, both pages show up looking almost exactly the same. Whoever decided that the <center> tag should be eliminated as a redundancy was mentally deranged! What's the point in making a whole container div when you can make do with so much less! Uggh!
Apparently, the <b> tag is illegal too, and if you wanna use <br>, you gotta close the tag like so <br/>!! we're moving backward in time or trying to make some headway in a positive direction? Duh!
//end of rant (for the time being NEway. :o)