in the above you are using 3 diff classes with your table.
i could not find "headerlogo" in your style.css, but did find "headerbanner" in any case all you have to do is adjust the height of the td(s)

add this to your #headerbanner "height: 70px;" or your preferred height

and
define td#headerlogo

td#headerlogo {
height: 70px;
}

you could also do this other ways such as adding padding to the above classes. do not forget to remove cellspacing once you have this corrected.