Firefox alignment different for IE

[exousia]

Could someone please tell me why on the following link www.aufad.org/08temp.html the page is centered in firefox but not in IE.

I've posted the code below just in case someone would rather see the code.

/* CSS Document */

body
{
margin:0px auto;
background-color: #ccffcc;
height:1000px;
}

#container
{
border: solid 1px #99cc99;
height:1000px;
width:800px;
margin:0px auto;
}

#header
{
width:798px;
height:188px;
}

#Elinkside
{
background-color:#99cc33;
float:left;
width:120px;
height:812px;
top:189px;
padding:5px;
font-size:1.5em;
}

a:link
{
color:black;
}

a:visited
{
color:black;
}

a:hover
{
color:#669900;
background-color: white;
}

#content
{
color:black;
float:left;
height:812px;
top:189px;
width:520px;
padding:5px;
margin-top: 5px;

}

.sponsor
{
float:left;
height:150px;
top:189px;
width:140px;
background-color:#FFFFCC;
color:black;
text-align:center;
}

Thank you

[Tyssen]

Because your doctype is incomplete and IE is in quirks mode. Fix your doctype and it should be right.