OK found it..
in the theme .css find..
#header {
position: relative;
height: 139px;
overflow: hidden;
background: url(./images/img/head.gif) 0 0 repeat-x;
}
#logo {
position: absolute;
top: 30px;
left: 20px;
display: block;
width: 346px;
height: 50px;
cursor: pointer;
background: url(./images/img/logo.png) no-repeat;
Replace with
#header {
position: relative;
height: 180px;
overflow: hidden;
background: url(./images/img/head.gif) 0 0 repeat-x;
}
#logo {
position: absolute;
top: 25px;
left: 20px;
display: block;
width: 600px;
height: 150px;
cursor: pointer;
background: url(http://i33.tinypic.com/2e3wjzr.jpg) no-repeat;
Then replace the head.gif img, with this one below, in Themes/halloween09/images/img
Also try un-checking "Enable News?" in current theme.
You can use either banner, but I have gone with the first img, I think the colors go better with the Halloween theme