I have been able to set the size of cells within tables for several years.  
The sum of the width of cells and borders and padding across a table equals
the width of the table.  My old web sites created on older versions of
FrontPage still maintain their sizing.  I specify the sizes; they stick. But
sites I build on FP2003 hold their cell sizes (specified or not, formatted or
not) through only a few workings and adjustments, then they begin to have a
mind of their own.  I adjust the content of a cell and another cell in
another area of the table changes size.  I readjust that wayward cell and a
new cell volunteers to appear on the other side of the table.  I delete that
cell and some new bastard adjustment appears elsewhere.  This has gone on for
months during which I have read manuals and talked to other users and
returned to pour another thirty or forty hours of patient work into these
tables from hell.  And the cells keep morphing with every click or insert or
letter added or changed.  I am missing something.  What is it?