@KravvitzAug 22.2007 — #IE4-6/Win won't let an element have a height that is less than its line-height. To fix this you can decrease the font-size and line-height OR use overflow:hidden.
@macthewebAug 22.2007 — #One solution is to zero out your margins and padding at a higher level using something like:
body * {marign: 0; padding:0; }
Of course if you do that you will have to reset all attributes for all elements. That's not as bad as it sounds. Do it well once then you can reuse the new stylesheet as a basis for all later projects. Look at Yahoo User Interface, Mollio and Blueprint for some well thought out and completer examples.