issues w/ float? IE vs. FF problems

I have nearly everything displaying relatively close in exactness.
Except when I load a table listing of categories for a section in joomla.

FF displays fine.. see below..


IE wraps the mainbody content below the left navigation


I have been doing a bunch of searching through css hacks, problems in IE, etc. but I haven't found any fix to this.

any help would be much appreciated.

CSS code below.

/* // dummyproof: netxecute dummyproof template
   // PHP Licence Details
   // copyright: (C) www.netxecute.com
   // license: GNU/GPL License
   // by Tristan McKerracher
   // of netxecute
   // __ http://www.netxecute.com
   // Published 28 May 2006
*/

body {
	margin : 0; 
	padding : 0; 
	text-align : center;
	font-size: 77%;
	font-family : "Lucida Grande","Lucida Sans Unicode",geneva,arial,verdana,sans-serif; 
	background : white; 
}

/* START SITE & DIV STYLES */
/* Used for layout of the SiteArea container div */
#SiteArea {

}
/* Used for layout of the SiteContent container div */
#SiteContent {
	width: 1024px;
	margin-left: auto;
	margin-right: auto;
}

/* START HEADER & POSITION STYLES */
/* Used for layout of the Header container div
Child of SiteArea/SiteContent */
#Header {
	height: 250px;
}
/* Used for layout of the icon position (ie. logo)
Child of Header */
#Icon {
	float: left;
}
/* Used for layout of the top position (ie. rightside of header)
Child of Header */
div>#TOP {
	width: 40%;
	margin-left: 55%;
}
#Top {
	height: 250px;
	margin-left: 50%;
	width: 80%;
}
/* END HEADER & POSITION STYLES */

/* START CONTENT & POSITION STYLES */
/* Used for layout of the Content container div
Child of SiteArea/SiteContent */
#Content {
	border-top: 10px solid #000000;
	border-right: 10px solid #000000;
	max-width: 760px;
}
/* Used for layout of the user5 position
Child of Left */
#User5 {
	
}
/* Used for layout of the left position
Child of Content */
#Left {
	float: left;
}
/* Used for layout of the user4 position
Child of Left */
#User4 {
	
}
/* Used for layout of the advert2 position
Child of Left */
#Advert2 {
	
}

/* Used to highlight various small bits of text */
.redtext {
	color: #FF0000;
}
/* Used for layout of the MainBody div
Child of Content */
#MainBody {

}
/* Used for layout of the user1 position
Child of MainBody */
div>#User1 {
	margin-left: 45%
}
#User1 {
	text-align: left;
	margin-left: 10%;
	float: left;
}
/* Used for layout of the user2 position
Child of MainBody */
div>#User2 {
	margin-left: 0%;
	margin-top: 0%;
}
#User2 {
	text-align: left;
	margin-left: 80%;
	margin-top: -18%;
}

/* Used for layout of the right position
Child of Content */
div>#Right {
	width: 20%;
}
#Right {
	width: 100%;
	margin-left: 80%;
	vertical-align: top;
}
/* Used for layout of the advert3 position
Child of Right */
#Advert3 {
	
}
/* END CONTENT & POSITION STYLES */

/* START FOOTER & POSITION STYLES */
/* Used for layout of the Footer container div
Child of SiteArea/SiteContent */
#Footer {
	clear: both;
	background-color: #7B9ECE;
}
/* Used for layout of the user3 position
Child of Footer */
#User3 {

}
ul#mainlevel-ftrmenu {
  list-style: none;
  padding: 0;
  margin: 0;
}
ul#mainlevel-ftrmenu li {
  background-image: none;
  padding-left: 0px;
  padding-right: 0px;
  margin: 0;
  float: left;
  font-size: 1em;
  white-space: nowrap;
}
ul#mainlevel-ftrmenu li a {
  display: block;
  padding-left: 15px;
  padding-right: 15px;
  text-decoration: underline;
  color: #B5CAE7;
}
ul#mainlevel-ftrmenu li a:hover {
  text-decoration: none;
  color: #FF0000;
}

/* Used for layout of the Designer div
Child of Footer */
#Designer {

}
/* Used for layout of the Copyright div
Child of Footer */
#Copyright {

}
/* Used for layout of the advert1 position (ie. header center)
Child of Footer */
#Advert1 {

}
/* END FOOTER & POSITION STYLES */

/* START JOOMLA STYLES */

/* Used for presentation of all module containers */
.moduletable {
	width: 100%;
}
.moduletable h3 {
	font-size: 1.2em;
	font-weight: bold;
	text-transform: uppercase;
	text-align: left;
	text-indent: 8px;
	letter-spacing: 1px;
	color: #7B9ECE;
}
.moduletable td {
	padding: 0 0 0 0;
	margin: 4px;
}

/* Used for presentation of all the user3 module position */
div.moduletable-ftrmenu {
	margin-left: auto;
	margin-right: auto;
}
.componentheading {
	text-align: left;
	font-size: 2em;
	font-style: italic;
	color: #7B9ECE;
}
.contentheading {
	text-align: left;
	font-size: 2em;
	font-style: italic;
	color: #7B9ECE;
}

Code (markup):