It displays better if you surround the google code with a centered table.
Here is an example of the end result and surrounding lines:
-Raymond
PHP Code:
alt="$vbphrase[post_new_thread]" border="0" /></a><else /> </if></td>
<td align=center>
<script type="text/javascript"><!--
google_ad_client = "pub-YOURCODE";
google_ad_width = 468;
google_ad_height = 15;
google_ad_format = "468x15_0ads_al";
google_color_border = "1e519b";
google_color_bg = "1e519b";
google_color_link = "FFFFFF";
google_color_text = "FFFFFF";
google_color_url = "008000";
//-->
</script>
<script type="text/javascript"
src="http://pagead2.googlesyndication.com/pagead/show_ads.js">
</script>
</td>
<if condition="$pagenav"><td align="$stylevar[right]">$pagenav</td></if>
</tr>
</table>