Are you looking for something like this?
for each (row)
<div class="row" style="height:cell-height">
for each (cell)
<div class="cell" style="width:cell-width/total-width+"%""> (..here Content of current Cell..) </div>
<!-- style -->
Of cause, this would only work if you have a really simple table layout with no rowspan. I'm not 100% sure, but i think with a little effort it would be possible to automate this transformation even for more complex layouts. You could use for example XSL transformations to achieve what you want.
But if you just have to rewrite a few documents, then it might be really faster to edit them by hand than to write yourself a transformation algorithm.