It requires the YUI module from drupal.org in order to be installed.
This is a modified version of the YUI editor that supports paste from Microsoft Word and alikes.
It uses the Rich Text Clean Paste plugin.
Well in the past I’ve tried it and couldn’t get it to work with YUI editor. It’s IMHO the best looking RTE out there, furthermore the advanced configuration provided, like profiles, toolbar customization and such are quite nice. So due to my not very positive impressions of YUI with WYSIWYG I’ve settled for this module.