Mail problems on new install

[conjurer]

I updated to run PHP 5.16 on Apache 2.0.54

I used to get the mail function to work under php 4 using the following in the PHP.ini file:

[mail function]
; For Win32 only.
SMTP = mail.xyz.net

; For Win32 only.
sendmail_from = [e-mail]

Now when I try to process a feedback form that was working under PHP4 I am getting the following warning/error:

Warning: mail() [function.mail]: Failed to connect to mailserver at "localhost" port 25, verify your "SMTP" and "smtp_port" setting in php.ini or use ini_set() in C:\Documents and Settings\RLane\My Documents\Web Sites\Localhost\InDevelopment\Wellington\Source\04\processfeedback.php on line 14

The code in processfeedback.php is as follows:

//create short variable names
  $name=$_POST['name'];
  $email=$_POST['email'];
  $feedback=$_POST['feedback'];

  $toaddress = '[e-mail]';
  $subject = 'Feedback from web site';
  $mailcontent = 'Customer name: '.$name."\r\n"
                 .'Customer email: '.$email."\r\n"
                 ."Customer comments: \r\n".$feedback."\r\n";
  $fromaddress = 'From: [e-mail]';

  mail($toaddress, $subject, $mailcontent, $fromaddress);

Any ideas what I need to modify to make it work?