Go to templates > main > template.tpl (open in a file editer). Find this line:
PHP Code:
<tr><td colspan="2" id="image"><span><a href="{$path}index">{$site_name}</a></span></td></tr>
And just move it directly above this line:
PHP Code:
<tr><th colspan="2">{$menu}</th></tr>
That should do the trick!