Could someone take a look at this?

[Camgaertner]

PHP Code:

<div id="container">
        <a name="top" id="top"></a>
        <div id="header">
            <div class="logo"><center><a href="{$mybb->settings['bburl']}/index.php" ><img src="{$theme['logo']}" alt="{$mybb->settings['bbname']}" title="{$mybb->settings['bbname']}" /></a></center></div>
</div>
<br style="clear:both;" />

        <div id="content">


<div class="menu">
<table class="tborder" border="0" cellpadding="4" cellspacing="1">
        
<tr> 
            <center><a href="{$mybb->settings['bburl']}/index.php"><img src="{$mybb->settings['bburl']}/{$theme['imgdir']}/icons/home.png" alt="Home" title="Home" /><strong><a href="{$mybb->settings['bburl']}/index.php">Home</a></strong></td>&nbsp;
<a href="{$mybb->settings['bburl']}/memberlist.php"><img src="{$mybb->settings['bburl']}/{$theme['imgdir']}/icons/
memberlist.png" alt="Memberlist" title="Memberlist" /><strong><a href="{$mybb->settings['bburl']}/memberlist.php">Memberlist</a></strong></td>&nbsp;
                                                <a href="{$mybb->settings['bburl']}/search.php"><img src="{$mybb->settings['bburl']}/{$theme['imgdir']}/icons/search.png" alt="Search" title="Search" /><strong><a href="{$mybb->settings['bburl']}/search.php">{$lang->toplinks_search}</a></strong></td>&nbsp;
                                                <a href="/iphone"><img src="{$mybb->settings['bburl']}/{$theme['imgdir']}/icons/mobile.png" alt="Version for Mobile Devices" title="Mobile" /><strong><a href="/iphone">Mobile</a></strong></td>&nbsp;
            <a href="{$mybb->settings['bburl']}/contact.php"><img src="{$mybb->settings['bburl']}/{$theme['imgdir']}/icons/contact.png" alt="Contact Form" title="Contact" /><strong><a href="{$mybb->settings['bburl']}/contact.php">Contact</a></strong></td>&nbsp;
            <a href="{$mybb->settings['bburl']}/misc.php?action=help"><img src="{$mybb->settings['bburl']}/{$theme['imgdir']}/icons/help.png" alt="Help Section" title="Help" /><strong><a href="{$mybb->settings['bburl']}/misc.php?action=help">{$lang->toplinks_help}</a></strong></td>
    </tr>
<br>
</table>
</center>
</div>
<hr class="hidden" />
            <div id="panel">
                {$welcomeblock}
            </div>
        </div>
        <hr class="hidden" />
        <br class="clear" />
        <div id="content">
            {$pm_notice}
            {$bannedwarning}
            {$bbclosedwarning}
            {$unreadreports}
            {$pending_joinrequests}
<center><script type="text/javascript"><!--
google_ad_client = "ca-pub-2926433416326194";
/* SHF */
google_ad_slot = "4241149195";
google_ad_width = 728;
google_ad_height = 90;
//-->
</script>
<script type="text/javascript"
src="http://pagead2.googlesyndication.com/pagead/show_ads.js">
</script></center>
<br>
            <navigation> 


I'm having a lot of trouble with my W3 Validation on this one. Mostly having to do with the center tags and whatnot.

Here's the validation log. Thanks for any help guys.

[AceInfinity]

Why not placing the <center> tags outside of the div, to center the entire thing instead of trying to center it within the div?

Also with XHTML, there's a few differences that you need to take note of, which I can't quite point out to you within this small block of code.

Edit:

PHP Code:

<div id="container">
    <a name="top" id="top"></a>
        <div class="logo" id="header">
            <a href="http://schoolhelpforums.net/index.php">
            <img src="http://schoolhelpforums.net/images/logo.jpg" alt="School Help Forums" title="School Help Forums" /></a>
        </div>
<br /> 


and instead of using a style directly in the line break, try using a class instead, and use css to change it specifically.

Don't use the center tags, change the css instead, or center the div if you have to.

Change the links if you want too, it's probably better to use the mybb definers instead "{$mybb->settings['bburl']}" and the other for the logo.