Sometimes, you need a table to spread out over the full page. You may have, for instance, a menu bar with a fixed height in the top row, a content row and a bottom row containing perhaps copyright notices.
For starters, set html and body to height:100%. This ensures that your table will assume maximum height.
For IE7, this does not seem to be enough, however. I have found that IE7 stretches the top and bottom row, ignoring their fixed height. Deleting the DOCTYPE declaration fixes this. See this MS page for more details on the “DOCTYPE switch”.
Adding a DOCTYPE declaration, any DTD, seems to mess up IE7's ability to properly display tables with height:100%.