[KarlRoos]

.menublock
{
background:url(../image_layout/layout_menu_m.png) repeat-x; /*THEME CHANGE HERE*/
height:32px;
text-align:center;
float: left;
}
.menublock_left
{
background:url(../image_layout/layout_menu_l.png) no-repeat; /*THEME CHANGE HERE*/
width:13px;
height:32px;
float: left;
}
.menublock_right
{
background:url(../image_layout/layout_menu_r.png) no-repeat; /*THEME CHANGE HERE*/
width:13px;
height:32px;
float: left;
}
.clear
{
clear: both;
}

<div>
<div class="menublock_left"></div>
<div class="menublock">Hej</div>
<div class="menublock_right"></div>
<div class="clear"></div>
</div>

Om jag har förstått rätt så borde detta fungera.