Once you go CSS you won't go back. It gives you freedom you can't get with tables and the basic subset of HTML/XHTML tags.
Here are some resources to add to the ones mentioned above:
http://www.simplebits.com/notebook/2...centering.html
^ Centering a layout.
http://www.alistapart.com/articles/practicalcss/
^ Positioning DIVs
PornoTGB's resource looks great too. Look at other people's CSS. I've got some of the IE hacks in my style sheets like the 'minimum height' fix.
You'll find you will need some tricks to get IE showing the same results as Mozilla-based browsers like Firefox and Netscape. Microsoft doesn't believe in the CSS standard and it shows in their support of it.