To be honest, there's a lot wrong with your page but I have done the minimum to get it to display as you want.
Add a doctype right at the top of the html page before the <html> tag:-
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN"
"http://www.w3.org/TR/html4/strict.dtd">
The tree outline needs to be at the top left of the screen so I moved the start of the div to just after the wrapper div so that it starts higher up and encloses the lower divs:-
.........<div id="wrapper">
<div id="WrapperOverlay">
<div id="TopText">........
but the closing tag is still in the same place:-
.............</form>
</div>
<!--<div id="WrapperOverlay2">opening tag moved up near top-->
</div> <!--end of #WrapperOverlay-->
<div id="footer">..........
Some changes were needed in the css file:-
adding left:0 in #WrapperOverlay
#WrapperOverlay {
width: 1000px;
height: 838px;
margin: 0;
top: 0; left: 0; /*left added*/
padding: 0 0 0 0;
background: url("/images/bg_overlay.png");
background-repeat: repeat-none;
background-position:center top;
background-attachment:scroll;
position:relative;
z-index: 5;
}
and I raised the #Mailing List:-
#MailingList {
width: 174px;
height: auto;
padding: 0 0 0 0;
position:relative;
top: 700px;/*was 850px;*/
left: 10px;
z-index: 15;
}
It seems to be OK in IE6, IE7, Firefox, Opera and Safari for Windows.
Code downloaded to my PC will be deleted in due course.
WIN7; IE9, Firefox, Opera, Chrome and Safari for Windows; screen resolution usually 1366*768.
Also IE6 on W98 with 800*600 and IE8 on Vista 1440*900.