In *some* Windows systems, setting LC_TIME only will not work, you must either set LC_ALL or both LC_CTYPE and LC_TIME. BUT if you have already set LC_TIME using setlocale earlier in the script, dates will not be affected! For example:
<?php
setlocale(LC_TIME, 'greek');
setlocale(LC_CTYPE, 'greek');
?>
will not work, while
<?php
setlocale(LC_CTYPE, 'greek');
setlocale(LC_TIME, 'greek');
?>
will do the job.