I've got a simple site with a floating dashed line in the design. I used postion:absolute with z-index and it looks good in Firefox. In other browsers the left alignment is off. I've been searching, but can't find a good resolution. What am I missing?

Note: Don't give me a hard time about the tables. I was under a deadline, so had to do it quick. I'll replace them with css later.

Site: www.prolitho.com/tpi

CSS:
Code:
body{
	background-color:#E46822;
	background-image:url(images/back.jpg);
	font-family:Arial, Helvetica, sans-serif;
	font-size:14px;
	color:#534545;
	padding:0;
	margin:0;
}

.white_hdr{
	width:800px;
	padding-left:20px;
	background-color:#FFF;
	-moz-border-radius: 0 0 15px 0;
	border-radius: 0 0 40px 0;
	text-align:left;
	padding-bottom:60px;
}

.orange{
	color:#E46822;
}

.hdr_txt{
	margin-left:40px;
	font-size:18px;
}
.hdr_img{
	float:left;
}

.gray_copy{
	width:800px;
	padding-left:20px;
	text-align:left;
	background-color:#F0E8E5;
	background-image:url(images/gray_back.jpg);
	background-repeat:no-repeat;
	-moz-border-radius: 0 0 15px 0;
	border-radius: 0 0 40px 0;
	margin:10px 0 20px 0;
}

.star{
	float:right;
	padding-top:4px;
}

.new{
	margin-top:50px;
	font-size:20px;
	font-weight:bold;
	text-align:center;
}

.bullet{
	padding: 30px 3px 0 3px;
}

.since{
	width: 50%;
	padding: 30px 25px 0 3px;
}

.info{
	padding: 3px 10px 0 0;
	font-size:12px;
}

.data_bullet{
	padding: 4px 10px 0 0;
}

.btm_imgs{
	text-align:center;
	padding:20px 0 20px 0;
}

.line{
	width:880px;
}

.dashed{
	position:absolute;
	margin:10px 0 0 0;
	left:370px;
	z-index:2;
}

.main{
	position:relative;
}
HTML:
Code:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<title>Travel Products Inc.</title>

<link rel="stylesheet" type="text/css" href="tpi_main.css" />
</head>

<body>
<div align="center" class="main">
    <div class="white_hdr">
        <img src="./images/tpi_hdr.jpg" width="330" height="158" class="hdr_img" />
        <img src="./images/spacer.gif" width="1" height="98" />
        <span class="hdr_txt">
            <span class="orange">YOUR PRODUCT&nbsp;&nbsp;&nbsp;|&nbsp;&nbsp;&nbsp;</span>
            protected &amp; portable
        </span>
    </div>
    <div class="line">
    	<img src="images/dashed.gif" width="880" height="8" class="dashed" />
    </div>
    <div class="gray_copy">
    	<table border="0" cellpadding="0" cellspacing="0">
        	<tr>
            	<td valign="top" class="bullet">
                	<img src="images/orange_sq.jpg" width="14" height="13" />
                </td>
        		<td valign="top" class="since">
    				Since 1981, <b>Travel Products, Inc.</b> has partnered with clients to create unique carrying cases made of strong, durable and lightweight materials.  All bags/cases are created 
                    to fit their product's form and function - bags and cases that are as beautiful as they are functional.
                    <p>
                    	TPI specializes in creating enclosures for medical devices, electronics/instrumentation, health and safety products, sales demo cases and much more.  Made for both industrial 
                        and commercial uses the carrying cases are made to last.
                    </p>
                    <p>
                    	<b>From design to concept to manufactured product</b>, TPI can blend your ideas with their expertise to ensure the right solution for your product.
                    </p>
                </td>
                <td valign="top" class="info">
                	<img src="images/star.gif" width="175" height="171" class="star" />
                    <p class="new">
                    	New TPI Web site,<br />
                        Coming Soon!
                    </p>
                    <p>
                    	<table border="0" cellpadding="0" cellspacing="0">
                        	<tr>
                            	<td valign="top">
                        			<img src="images/orange_sq.jpg" width="14" height="13" class="data_bullet" />
                                </td>
                                <td>
                                    <b>
                                        2401 49th Avenue North<br />
                                        Minneapolis, MN 55430<br /><br />
                                        800.588.8230 toll free<br />
                                        612.588.8230<br />
                                        612.588.8230 fax<br /><br />
                                        customerservice@travelproductsinc.com
                                    </b>
                                </td>  
                            </tr>
                        </table>                 
                    </p>
                </td>
           	</tr>
        
        </table> 
        <div class="btm_imgs">
        	<img src="images/fp1.jpg" width="109" height="109" />
            <img src="images/spacer.gif" width="10" height="1" />
            <img src="images/fp2.jpg" width="109" height="109" />
            <img src="images/spacer.gif" width="10" height="1" />
            <img src="images/fp3.jpg" width="109" height="109" />
            <img src="images/spacer.gif" width="10" height="1" />
            <img src="images/fp4.jpg" width="109" height="109" />
            <img src="images/spacer.gif" width="10" height="1" />
            <img src="images/fp5.jpg" width="109" height="109" />
            <img src="images/spacer.gif" width="10" height="1" />
            <img src="images/fp6.jpg" width="109" height="109" />
        </div>
    </div>
</div>
</body>
</html>