If I'm not wrong, your banner image is styled as an inline element and that explains why it is lined up with the Home link when the following HTML is displayed in your store.
HTML Code:
<img width="756" height="147" alt="" src="images/finalheader_2.jpg"/>
<a class="navtop1" href="/cart/index.php?main_page=index">Home</a>
You can try using CSS to style your image as a block element instead of the current inline element. To test this out using an inline CSS style, change the HTML for your image to:
HTML Code:
<img width="756" height="147" alt="" src="images/finalheader_2.jpg" style="display:block"/>
If that works for you, place the CSS style in your external stylesheet.