CSS - Ie6 Centering Question

I will preface this with the fact I am a newbie with CSS.

Site location - I would tell you where site was but against rules!

Question - site looks OK on everything except IE6 and lower. The body should be centered under the header image however it is pushed/alligned left. The CSS is below.

Can anyone see why this is happening and what a good fix would be?

Thanks

/* CSS Document */

body{
padding:0;
margin:0;}
form, div, p , ul, span, h2, h3, h4, h1,input, img{
padding:0;
margin:0;}
p{
color:#3D3B45;
font: 12px/normal Verdana, Arial, Helvetica, sans-serif}
ul{
list-style-type:none
}
img {
border:none;
}
.spacer{
font-size:0; line-height:0; clear:both;
}
/*---------------header-------------------------------*/
#main{
width:780px;
margin:0 auto 0 auto;
background:#FFFCEC;
}

#main #header{
width:780px;
height:175px;
background:#FFFCEC url(images/header.jpg) no-repeat 0 5px;
position:relative;
}

#header a.title{
position:absolute;
left:23px;
top:37px;
width:228px;
height:25px;
display:block;
}
#header h1.title a{
display:block; text-decoration:none;
}
#header ul.nav{
position:absolute;
left:566px;
top:5px;
background:url(images/nav.gif repeat-x 0 0 #FFFEE4;
width:213px;
padding:0px 0 18px 0;
margin:0;
}
#header ul.nav li{
background:url(images/h_line.gif) repeat-x left bottom;
font:bold 11px/normal Arial, Helvetica, sans-serif, Tahoma;
color:#484848;
width:197px;
padding:5px 0 5px 0;
}
#header ul.nav li a{
background:url(images/arrow.gif) no-repeat 0 5px;
margin:0 0 0 15px;
font:bold 11px/normal Arial, Helvetica, sans-serif, Tahoma;
color:#484848;
text-decoration:none;
padding:0 0 0 15px;
}
#header ul.nav li a:hover{
color:#000000;
}
/*------body-------*/
#main #left{
background:url(images/v_line.gif) repeat-y right top;
width:543px;
margin:0 0 0 0;
padding:15px 0px 0px 23px;
float:left;
}

#left h2.contact{
background:url(images/contact_wp.gif) no-repeat 0 0;
width:518px;
height:16px;
text-indent:-200000px;
}

#left h2.survty{
background:url(images/survty.gif) no-repeat 0 0;
width:518px;
height:32px;
text-indent:-200000px;
}

#left h2.welcome{
background:url(images/welcome_to_wp.gif) no-repeat 0 0;
width:518px;
height:35px;
text-indent:-200000px;
}

#left p.weltxt{
font: 12px/normal Verdana, Arial, Helvetica, sans-serif;
color:#3D3B45;
text-align:justify;
width:518px;
margin:0px 0 0 0;
}
#left p.weltxtsp{
font: 12px/normal Verdana, Arial, Helvetica, sans-serif;
color:#3D3B45;
text-align:justify;
width:518px;
margin:16px 10px 10px 0;
}

#left p.headingtext{
font: 12px/normal Verdana, Arial, Helvetica, sans-serif;
color:#3D3B45;
text-align:justify;
width:518px;
margin:10px 0px 10px 0;
}

#left p.weltxt a.more{
float:right;
padding:25px 0 21px 0;
color:#3D3B45;
text-decoration:none;
font-weight:bold;
}
#left p.weltxt a:hover{
color:#990000;
text-decoration:underline;
}
#left h2.rest{
background: url(images/catering.gif) no-repeat 0 0;
width:516px;
height:29px;
line-height:0;
font-size:0;
margin:20px 0 0 0;
text-indent:-200000px;
clear:both;
}
#left div.menu{
background:url(images/menu_bg.gif) repeat-x 0 0;
width:516px;
height:123px;
padding:11px 0 0 7px;
}
#left div.menu ul.brown{
float:left;
width:94px;
margin:0 8px 30px 0;
display:block;
}
ul.brown li{
background:url(images/brown.gif) no-repeat 0 8px;
padding:0 0 13px 10px;
color:#3D3B45;
}
ul.brown li a{
text-decoration:none;
color:#3D3B45;
font:bold 11px/normal Arial, Helvetica, sans-serif, Tahoma;
}
ul.brown li a:hover{
color:#990000;
text-decoration:underline;
}
#left h2.order{
background:url(images/directions2.gif) no-repeat 0 0;
width:513px;
height:26px;
text-indent:-200000px;
clear:both;
}
#left ul.image{
margin:15px 0 0 0;
width:520px;
}
#left ul.image li{
height:153px;
width:95px;
text-align:center;
margin:0 6px 0 0 ;
background:url(images/order_now.gif) no-repeat 14px 134px;
float:left;
font:bold 11px/normal Arial, Helvetica, sans-serif, Tahoma;
color:#3D3B45;
}
#left ul.image li span{
color:#B57D0A;
}
#left ul.image li a{
margin:0 0 0 0;
text-decoration:none;
color:#990000;
}
#left ul.image li a:hover{
color:#000000;
text-decoration:underline;}
/*------right----*/
#main #right{
width:200px;
background:url(images/right_bg.gif) repeat-x left bottom #FFFEE4;
float:left;
padding:25px 0 97px 13px;
}
#right h2.our{
background: url(images/location.gif) no-repeat 0 0;
width:145px;
height:15px;
text-indent:-200000px;
}
#right p.ourtxt{
font: 12px/normal Verdana, Arial, Helvetica, sans-serif;
color:#3D3B45;
text-align:justify;
width:168px;
margin:18px 0 0 0;
}
#right img{
margin:13px 0 0 0;
}
#right p.border{
width:178px;
height:5px;
margin:23px 0 0 0;
font-size:0;
line-height:0;
background:#FCF2B8;
}
#right p.ourtxt span{
color:#8F1401;
font:bold 12px/normal "Trebuchet MS",Helvetica, sans-serif, Tahoma;
}
#right p.ourtxt a{
color:#B57D0A;
font:bold 12px/normal "Trebuchet MS",Helvetica, sans-serif, Tahoma;
text-decoration:underline;
}
#right p.ourtxt a:hover{
color:#000000;
}
/*----footer-----*/
#footer{
width:780px;
position:relative;
background:url(images/footer_bg.gif) repeat-x 0 0 #FDF6D2 ;
clear:both;
height:168px;
}
#footer ul.foot{
position:absolute;
top:21px;
left:140px;
width:522px;
}
#footer ul.foot li{
float:left;
margin:0 14px 0 0;
color:#232323;
font:bold 11px/normal Arial, Helvetica, sans-serif, Tahoma;
}
#footer ul.foot li a{
text-decoration:none;
text-transform:uppercase;
color:#232323;
}
#footer ul.foot li a:hover{
color:#990000;
}
#footer p{
position:absolute;
top:43px;
left:324px;
text-align:center;
color:#232323;
font:normal 11px/20px Arial, Helvetica, sans-serif, Tahoma;
}

#footer p a{
color:#232323;
font:normal 11px/20px Arial, Helvetica, sans-serif, Tahoma;
text-decoration:underline;
}

#footer p a:hover{
text-decoration:none;
}