Why would images and tables have different sizes? I speciefied my table to be width=800, height=200 and the image fall in those dimensions.

I make my table border 1 so i can see if its right, and in Firefox, safari, ie for macs but in IE on windows there is more space on the bottom of the table by a couple pixels so the image doesn't fill it up anyone know why?

Code looks like this

Code:
		<table border=1 width=800 cellspacing=0 cellpadding=0 align=center>
			<tr>
				<td width=800 height=200 colspan=3>
					<img src='header.jpg'>
				</td>
			</tr>
                 </table>
only way i know to fix this problem is by doing
Code:
 <img src='header.jpg' width=100% height=100%>
or by setting the row width and height and then making the image the background

and im not really liking that...