The disadvantage of using table-layout is, once the entire table is loaded then only u can view it. This is a performance issue interms of user experience, for ex if u have table with hundred images, until all the images r loaded u cannot see them. Instead if u follow some other way like using div's, it might be good.
Also dont overwrite styles until unless they r explicitly required. This is because if u have color coming for a p element from two style rules then it is considered as an error in css validator checks.
Giving negative margins will mess up things in IE6.
