Thanks for your continued help! I definitely get the "cells fill all available space" concept. The thing is that these cells are in their own little widget table as per the "new widget areas" documentation:
Because these are multiple cells side by side, it will create a table instead of a DIV. Doing this with floating DIV's would not only be very fragile, it would also require more code than the table consists of.
It is this table that fills the available space through a style setting "width:100%;. So if a person wants to limit the width of a new widget area somewhere in the layout, it is as easy as setting the width of that table to a static width such as "width: 500px;"
I've included two screenshots of Firebug + my footer. The first is the relevant part of the code and what it does by default. The second shot, is the result of setting "width: 600px;" and "margin-left: auto;" and "margin-right:auto;" This gives the desired effect. BUT, I only know how to achieve this effect by editing the code directly in firebug.
Optimally, this could be done through html inserts but i have NO idea how. Any help on this end of things would be greatly appreciated. The other option is of course, finding the table in the ATA code and simply editing it, but that seems to be frowned upon (for obvious reasons) around these parts.