debugx,
 
Ту не так нужно это нифига не даёт таблицы это особенный зверь....
Таблицу распирает неразрывная последовательность....
есть два варианта с лишним дивом 
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
        "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>тест</title>
<meta http-equiv="content-type" content="text/html; charset=utf-8" />
  <style type="text/css">
	body{
	width:1000px;
	}
	table{
	width:100%;
	}
	table td{
	border:1px solid red;
	}
	table div{
	width:100px;
	word-wrap:break-word;
	}
  </style>
 </head>
 <body>
  <table>
	<tr>
		<td><div>afadfafadfafadfafadfafadfafadfafadfafadfafadfafadfafadfafadfafadfafadfafaafadfafadfafadfafadfafadfafadfafadfafadfafadfafadfafadfafadfafadfafadfafadfafadfafadfafadfdfafadfafadfafadf</div></td>
		<td>afadf</td>
		<td>afadf</td>
		<td>afadf</td>
	</tr>
  </table>
  
 </body>
</html>
второй вариант без дива 
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
        "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>тест</title>
<meta http-equiv="content-type" content="text/html; charset=utf-8" />
  <style type="text/css">
	body{
	width:1000px;
	}
	table{
	width:100%;
	table-layout:fixed;
	}
	table td{
	border:1px solid red;
	word-wrap:break-word;
	}
  </style>
 </head>
 <body>
  <table>
	<tr>
		<td>afadfafadfafadfafadfafadfafadfafadfafadfafadfafadfafadfafadfafadfafadfafaafadfafadfafadfafadfafadfafadfafadfafadfafadfafadfafadfafadfafadfafadfafadfafadfafadfafadfdfafadfafadfafadf</td>
		<td>afadf</td>
		<td>afadf</td>
		<td>afadf</td>
	</tr>
  </table>
  
 </body>
</html>