@jellby -- as stated above, setting a table width as a percent gives unexpected results.
@toxaris-- i'm coming from a web developer background. Are you sure ADE is modern? It doesn't support :before or :after for crying out loud. In many ways, it's just as bad as IE6.
Just tried two tables one wrapped in a DIV and the other in a P. Neither centered horizontally. Will double-check my code and report back if I get it to work.
But for now I'm giving up. I think I can live with tables with a fixed left margin or correctly centered everywhere else.
However, for images, setting a width as a percent and margin-left also as a percent is an excellent idea I'll be using.