This can be done by changing this table code in inc_top.asp:
<table align="center" border="0" cellPadding="0" cellSpacing="0" width="100%">
<tr>
<td valign="top" width="50%"><a href="default.asp"><img alt="<% =strForumTitle %>" border="0" src="<%=strTitleImage%>"></a></td>
<td align="center" valign="top" width="50%">
<table border="0" cellPadding="2" cellSpacing="0">
<tr>
<td align="center"><font face="<% =strDefaultFontFace %>" size="<% =strDefaultFontSize %>"><b><% =strForumTitle %></b></font></td>
</tr>
<tr>
<td align="center"><font face="<% =strDefaultFontFace %>" size="<% =strFooterFontSize %>">
<% call sForumNavigation() %>
</font></td>
</tr>
<%
select case Request.Form("Method_Type")
case "login"
%>
</table>
</td>
</tr>
</table>
<% if strLoginStatus = 0 then %>
<p align="center"><font face="<% =strDefaultFontFace %>" size="<% =strHeaderFontSize %>">Your username and/or password were incorrect.</font></p>
<p align="center"><font face="<% =strDefaultFontFace %>" size="<% =strHeaderFontSize %>">Please either try again or register for an account.</font></p>
<% else %>
<p align="center"><font face="<% =strDefaultFontFace %>" size="<% =strHeaderFontSize %>">You logged on successfully!</font></p>
<p align="center"><font face="<% =strDefaultFontFace %>" size="<% =strHeaderFontSize %>">Thank you for your participation.</font></p>
<% end if %>
<meta http-equiv="Refresh" content="2; URL=<% =Request.ServerVariables("HTTP_REFERER") %>">
<p align="center"><font face="<% =strDefaultFontFace %>" size="<% =strDefaultFontSize %>"><a href="<% =Request.ServerVariables("HTTP_REFERER") %>">Back To Forum</font></a></p>
<% WriteFooter
Response.End
case "logout"
%>
</table>
</td>
</tr>
</table>