Login Invalid Script ASP/mySQL

I am using the following script allowing users to login, but I am having
trouble writing the portion that indicates an invalid username or password.

Any thoughts?


<%
set conn=server.createobject("ADODB.connection")
conn.open "DRIVER=MySQL ODBC 3.51
Driver;UID=;STMT=;OPTION=;PORT=;PASSWORD=;SERVER=; DATABASE=;DESC=;"
strSqlString = "select count(*) as counter, ID from tblxxxxxx where
username='"& request.form("Username") & "' and password=password('"&
request.form("Password")&"') group by ID"
set rs=conn.execute (strSQLString)
if cint(rs("counter")) <> 1 then
session("sblogin")=false
session("sbuid")=""
response.redirect("../system/login.asp")
else
session("sblogin")=true
session("sbuid")=rs("id")
%>