Hi, I have made a more advanced site (in terms of just starting to use css) than my last one in my quest to become more knowledgable in css.
Problem is, the boxes are not aligning properly.

Here is the code and a url, as you can see I have tried to get rid of my "divitis" please let me know if it has worked.

html:
Code:
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />
<title>Untitled Document</title>
<link href="stylesheet.css" rel="stylesheet" type="text/css" />
</head>

<body>
<div class="wrapper"> 
  <div class="top_nav">
    <div align="center">Home | Forums | Members | Recent Matches | Upcoming Matches | Leagues/Tournaments | Contacts | Links </div>
  </div>
<div class="top_nav"><center>
Your Drop-Down Menu <br>
</center></div>
</div>

<div class="clear_welcome">
  <div class="clear_welcome_bar">
    <div id="clear_bar_text"><br />
      <br />
      <br />
    &nbsp;&nbsp;&nbsp;&nbsp;Welcome to the site guest, please login </div>
  </div>
  <div class="banner"><img src="images/banner.jpg" width="870" height="159" /></div>
</div>
<div class="ad_banner">
  <div class="ad_banner_content">
    <div class="ad_right"><img src="images/right_ad.jpg" /></div>
	  <div class="ad_top"><img src="images/top_ad.gif" width="799" height="29" /></div>
        <div class="ad_left"><img src="images/left_ad.gif" /></div>
         <div class="ad_image"><img src="images/test.jpg" width="795" height="71" /></div>
          <div class="ad_bottom"><img src="images/bottom_ad.gif" width="799" height="29" /></div>
	 
</div>
<div class="left_content_wrapper">
	<div class="left_content_top">Welcome to the Site! </div>
		<div class="left_content_mid">
		  <p>Hello, this is the content. As you move down the content box shall expand. Please note that if a browser with the capability to increase text size is used, the text size on the site will increase but the images will stay the same, this gives greater accessibility allowing people with disabilities to view the site.</p>
		</div>
	<div class="left_content_bottom"></div>
  </div>
<div class="left_content_wrapper2">
	<div class="left_content_top">Here is another content box!  </div>
		<div class="left_content_mid">
		  <p>Hello, this is the content. As you move down the content box shall expand. Please note that if a browser with the capability to increase text size is used, the text size on the site will increase but the images will stay the same, this gives greater accessibility allowing people with disabilities to view the site.</p>
		</div>
	<div class="left_content_bottom"></div>
</div>
<div class="main_content_wrapper">
	<div class="main_content_top">This is the main content box</div>
		<div class="main_content_mid">
		  <p>Hello, this is the main content. Use this for site news etc.</p>
	</div>
	<div class="main_content_bottom"></div>
</div>
<div class="main_content_wrapper2">
	<div class="main_content_top2">This is the second content box </div>
		<div class="main_content_mid2">
		  <p>Hello, this is the larger content box, the box size can easily be changed in the css file. The ID is main_content_*2</p>
	</div>
	<div class="main_content_bottom2"></div>
</div>
	<div class="footer">Can be used as a second navigation&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;A site created by <a href="http://www.themediastudios.co.uk">The Media Studios</a>  </div>
</div>
</body>
</html>
CSS:
Code:
/*body style*/
body,td,th {
	font-family: Tahoma;
	color: #000000;
}
body {
	background-color: #FFFFFF;
}
a:link {
	color: #000000;
	text-decoration: underline;
}
a:visited {
	text-decoration: underline;
	color: #000000;
}
a:hover {
	text-decoration: none;
	color: #000000;
}
a:active {
	text-decoration: underline;
	color: #000000;
}
/*end of body style.
Wrapper holds all content*/
.wrapper {
	background-image: url(images/background.jpg);
	width: 900px;
	margin-right: auto;
	margin-left: auto;
	font-family: tahoma;
	font-size: 10px;
	color: #000000;
}
/*navigation at top of page*/
.top_nav {
	font-family: Tahoma;
	font-size: 10px;
	font-weight: bold;
	color: #000000;
	background-image: url(images/top_nav.jpg);
	width: 871px;
	margin-left: 14px;
	height: 21px;
	line-height: 180%;
}
.clear_welcome {
	font-family: tahoma;
	font-size: 10px;
	color: #000000;
	background-image: url(images/background.jpg);
	height: 100%;
	width: 900px;
	margin-right: auto;
	margin-left: auto;
}
.clear_welcome_bar {
	font-family: tahom;
	font-size: 10px;
	color: #000000;
	background-image: url(images/glass_bar_above_banner.jpg);
	height: 60px;
	width: 871px;
	margin-left: 14px;
}
.banner {
	height: 159px;
	width: 857px;
	margin-left: 14px;
}
.ad_banner {
	height: 129px;
	width: 900px;
	margin-right: auto;
	margin-left: auto;
	background-image: url(images/background.jpg);
}
.ad_banner_content {
	height: 129px;
	width: 863px;
	margin-left: 22px;
}
.ad_top {
	height: 29px;
	width: 799px;
}
.ad_left {
	height: 71px;
	width: 4px;
	float: left;
}
.ad_bottom {
	height: 29px;
	width: 799px;
	clear: left;
}
.ad_right {
	float: right;
	height: 129px;
	width: 64px;
}
.ad_image {
	height: 71px;
	width: 795px;
	float: left;
}
/*left content box top*/
.left_content_wrapper {
	width: 249px;
	height: 301px;
	margin-left: 22px;
	float: left;
}
/*left content box bottom*/
.left_content_wrapper2 {
	width: 249px;
	height: 301px;
	margin-left: 22px;
	float: left;
	clear: left;
}
.left_content_top {
	height: 28px;
	width: 249px;
	background-image: url(images/side_con_top.gif);
	background-repeat: no-repeat;
	font-family: tahoma;
	font-size: 10px;
	font-weight: bold;
	color: #000000;
	line-height: 25px;
	text-indent: 13px;
}
.left_content_mid {
	width: 249px;
	height: 100%;
	background-image: url(images/left_content_mid.gif);
	color: #000000;
}
.left_content_mid p {
	width: 232px;
	height: 264px;
	font-family: Tahoma;
	font-size: 11px;
	color: #000000;
	margin-left: 12px;
	margin-right: 5px;
}
.left_content_bottom {
	width: 249px;
	height: 9px;
	background-image: url(images/side_con_bottom.gif)
}
/*small content box*/
.main_content_wrapper {
	float: right;
	width: 605px;
	margin-right: 22;
	height: 100%;
}
.main_content_top {
	width: 605px;
	height: 21px;
	background-image: url(images/small_content_top.gif);
	font-family: Tahoma;
	font-size: 10px;
	font-weight: bold;
	color: #000000;
	line-height: 20px;
	text-indent: 13px;
	float: right;
}
.main_content_mid {
	background-image: url(images/small_content_mid.gif);
	height: 100%;
	padding-bottom: 12px;
}
.main_content_mid p {
	font-family: Tahoma;
	font-size: 11px;
	color: #000000;
	width: 572px;
	margin-left: 9px;
	height: 208px;
}
.main_content_bottom {
	background-image: url(images/small_content_bottom.gif);
	width: 605px;
	height: 5px;
}
/*larger content box*/
.main_content_wrapper2 {
	float: right;
	width: 605px;
	margin-right: 22;
	height: 100%;
}
.main_content_top2 {
	width: 605px;
	height: 21px;
	background-image: url(images/small_content_top.gif);
	font-family: Tahoma;
	font-size: 10px;
	font-weight: bold;
	color: #000000;
	line-height: 20px;
	text-indent: 13px;
	float: right;
}
.main_content_mid2 {
	background-image: url(images/small_content_mid.gif);
	height: 100%;
	padding-bottom: 12px;
}
.main_content_mid2 p {
	font-family: Tahoma;
	font-size: 11px;
	color: #000000;
	width: 572px;
	margin-left: 9px;
	height: 208px;
}
.main_content_bottom2 {
	background-image: url(images/small_content_bottom.gif);
	width: 605px;
	height: 5px;
}
.footer {
	background-image: url(images/footer.jpg);
	width: 900px;
	height: 81px;
	clear: both;
	font-family: tahoma;
	font-size: 10px;
	font-weight: bold;
	color: #000000;
	line-height: 76px;
	text-indent: 45px;
}
Here is the URL

I have tried a few things myself but I can't get it to align properly. Will keep trying until I get a few suggestions. Thanks a lot.
Stephen.