how about
function remove_access(){
remove_action('thematic_header','thematic_access',9);
remove_action('thematic_header','thematic_brandingopen',1);
}
add_action('init','remove_access');
add_action('thematic_header','thematic_access',9);
add_action('thematic_header','thematic_brandingopen',2);
function header_inner_open(){
echo '<div id="header-inner" class="clearfix">';
}
add_action('thematic_header','header_inner_open',1);
function header_inner_close(){
echo '</div><!--#header-inner-->';
}
add_action('thematic_header','header_inner_close',9);
and for css:
/* new clearfix
* http://perishablepress.com/press/2009/12/06/new-clearfix-hack/
*/
.clearfix:after {
visibility: hidden;
display: block;
font-size: 0;
content: " ";
clear: both;
height: 0;
}
* html .clearfix { zoom: 1; } /* IE6 */
*:first-child+html .clearfix { zoom: 1; } /* IE7 */
#header-inner{
width: 940px;
margin: 0 auto;
}
#branding{
width: 350px;
float: left;
}
#access{
width: 350px;
float: right;
}
you may need to do something w/ .menu too, but i'm not 100% sure.. i didn't fully test this, but it ought to get you the proper markup to do what you are trying to accomplish.