postbit help

i added new postbit today, as recommended here.

sample postbit

i cant get my posts to be as wide as the header bar (bar w/ new reply/topic, etc)
when i do make it correct width, it shows gray on sides (my bg color)


my code
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<table width="750" cellpadding="0" cellspacing="0" border="0">
<tr>
<td width="7" height="26" background="images/cat_bg.gif" valign="top">
<img border="0" src="images/cat_top_left.gif" width="7" height="26">
<td height="26" background="images/cat_bg.gif"> <a href="editpost.php?s=$session[sessionhash]&action=editpost&postid=$post[postid]"><img border="0" src="images/edit.gif" alt="Edit/Delete Message" width="56" height="16"></a><a href="newreply.php?s=$session[sessionhash]&action=newreply&postid=$post[postid]"><img src="images/quote.gif" border="0" alt="Reply w/Quote" width="56" height="16"></a></td>
<td width="200" background="images/cat_bg.gif"><div align="right"><img src="images/upperjoint.gif"></div></td>
<td height="26" background="images/cat_bg2.gif" width="50%"><div valign="top" align="right">$onlinestatus<img src="images/cat_top_right.gif"></div></td>
</tr>
</table>
<tr>
<table width="750" cellpadding="0" cellspacing="0" border="0">
<td width="144" valign="top" background="images/user_info_bg.gif" nowrap>
<p align="center"> <a name="post$post[postid]"></a> $post[firstnewinsert]
<normalfont><br>
$post[avatar]<table><td height="5"></td></table>
<div align="center"><normalfont><b>$post[username]</b></normalfont><br><br><b>
<font face="verdana" color="#003D75" size="1">User Info >></font></font><table><td height="1"></td></table></div>
<table align="center" border="1" cellpadding="0" cellspacing="0" style="border-collapse: collapse" bordercolor="#111111" width="80%">
<td height="10" bgcolor="#F8F8F8"> <div align="center"><smallfont><b>
TITLE: $post[usertitle]</b></smallfont></div></td></tr>
</table>
<table><td height="2"></td></table>
<table align="center" border="1" cellpadding="0" cellspacing="0" style="border-collapse: collapse" bordercolor="#111111" width="80%">
<td height="10" bgcolor="#F8F8F8"> <div align="center"><smallfont><b>POSTS:
$post[posts]</b></smallfont></div></td></tr>
</table><table><td height="2"></td></table>
<table width="80%" border="1" align="center" cellpadding="0" cellspacing="0" bordercolor="#111111" style="border-collapse: collapse" dwcopytype="CopyTableRow">
<td height="10" bgcolor="#F8F8F8"> <div align="center"><smallfont><b>JOINED:
$post[joindate]</b></smallfont></div></td></tr>
</table>
<p align="center">$post[profile] $post[useremail]<br>
$post[homepage] $post[buddy]
<p>
<td bgcolor="$post[backcolor]" width="100%" valign="top"><smallfont>$post[icon]
<b>$post[title]</b></smallfont> <p><normalfont>$post[message]</normalfont></p>
$post[attachment]
<p>$post[signature]</p>
<p>$post[editedby]</p>
<p align="right"><smallfont><a href="report.php?s=$session[sessionhash]&postid=$post[postid]">Report
this post to a moderator</a> | $post[iplogged]</smallfont></td>
<tr>
</table>
<table width="750" cellpadding="0" cellspacing="0" border="0" valign="top">
<tr><td width="7" height="26" background="images/cat_bg4.gif" valign="top"><img border="0" src="images/cat_bottom_left.gif">
<td height="26" background="images/cat_bg4.gif">&nbsp; </td>
<td width="200" background="images/cat_bg4.gif">
<div align="right"><img src="images/lowerjoint.gif"></div></td>
<td height="26" background="images/cat_bg3.gif" width="50%"><div valign="top" align="right">
<div align="right"><a valign="middle">$post[pmlink] $post[search]</a></div></td><td background="images/cat_bg3.gif"></td>
<td background="images/cat_bg3.gif"><div align="right"><img src="images/cat_bottom_right.gif"></div></td>
</tr>
</table>


<table bgcolor="#ffffff" width="{pagewidth}" cellpadding="0" cellspacing="0" border="0">
<table bgcolor="#ffffff" width="750"><td height="10"></td></table>

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any ideas?