JDBC driver not found error: Windows XP / JDK1.6.06 / PG8.2.9

I have PostgreSQL 8.2.9 on Windows XP, with JDK 1.6.0_06.   Have got the postgresql-8.2-508.jdbc4.jar  jdbc driver in /lib/ext of the Java folder.

HAve set both the PATH and CLASSPATH aporpriately

My Java code for testing is:

import java.sql.*;

class postgreSQLTest
 {

public static void main (java.lang.String[] args) throws Exception {

try{

Class.forName("org.postgresql.Driver");

Connection con =
DriverManager.getConnection("jdbc:Postgresql://localhost:5432/postgres","postgres","1234");

Statement stmt = con.createStatement();
ResultSet rs = stmt.executeQuery("select * from country");

while(rs.next())

{

System.out.println(rs.getString(1)+"<br>");

}

}catch(Exception e){

System.out.println(e);

}

}

}

But I get the error
Exception in thread "main" java.lang.NoClassDefFoundError: postgreSQLTest