Is this login system secure

Is this login system secure ?

    if ($_POST[$submit]){$user = $_POST[$user];$pass = $_POST[$pass];if ($user && $pass){ //if user and pass is enterered        require("vars.php"); //require MySQL conection settings        mysql_connect($auth_mysql_server, $auth_mysql_user, $auth_mysql_pass); //connect to MySQL        mysql_select_db($auth_mysql_db); // select MySQL database        $pass = md5($pass); // hash password        $query = mysql_query("SELECT * FROM $auth_mysql_table WHERE user='$user'"); // run query        $numrows = mysql_num_rows($query);        if ($numrows == 1){ //check if user exists            $row = mysql_fetch_assoc ($query);            $dbid = $row[$auth_mysql_id_row];                $dbuser = $row[$auth_mysql_user_row];                $dbpass = $row[$auth_mysql_pass_row];                if ($pass == $dbpass){ // if password is equal to the one in the database start session                    session_start();                    //set session information                    $_SESSION['user'] = $dbuser;                    header("Location:$auth_loggedin"); // goto logged in page                }                else return (3);        }        else return (2);        mysql_close(); // close MySql connection    }    else return (1);}

If not how could i make it secure ?

I hashed the password but i know md5 can be decrypted however sha1 can be too.Also is themysql_close() needed ?