100% height for table?

<table style="margin: 0 auto; height: 100%;" align=center width=780>
<tr><td height=150 width="100%"> HEADER </td></tr>
<tr><td valign=top> BODY </td></tr>
<tr><td height=30> FOOTER </td></tr>
</table>

Look at the first line of the above code, style="margin: 0 auto; height: 100%;" this will give 100% height for the table, marin: 0 auto; means we specificaly saying the top margin should be zero and the rest (right, bottom and left) will be taken automaticaly.

Now take the header and footer cells, here we are specifying a fixed height. 150 for header and 30 for footer, this should vary accordign to your requirements. For the center cell (body area) we are going for a dynamicheight cell, so that we will not specify any height for this cell and it will stretch out all the way to the bottom of the page