Script:
<?php
    $key = "this is a secret key";
    $input = "Let us meet at 9 o'clock at the secret place.";

    $td = mcrypt_module_open ('tripledes', '', 'ecb', '');
    $iv = mcrypt_create_iv (mcrypt_enc_get_iv_size ($td), MCRYPT_RAND);
    mcrypt_generic_init ($td, $key, $iv);
    $encrypted_data = mcrypt_generic ($td, $input);
    mcrypt_generic_deinit ($td);
    mcrypt_module_close ($td);
?>

Modules:
extension=php_cpdf.dll
extension=php_curl.dll
extension=php_dbg.dll
extension=php_dbx.dll
extension=php_domxml.dll
extension=php_exif.dll
extension=php_gd.dll
extension=php_java.dll
extension=php_mcrypt.dll
extension=php_mhash.dll
extension=php_mime_magic.dll
extension=php_openssl.dll
extension=php_pdf.dll
extension=php_sockets.dll
extension=php_w32api.dll
extension=php_xmlrpc.dll
extension=php_xslt.dll
extension=php_zip.dll

Info:
The script provided is the same of the php mcrypt documentation.
It happens on NT4 and php 4.3.1 as well