There was default code in Sidebar_3, which would show "Top Rated Posts" if there is no function added by user. So, what happened was that as you pointed I forget to activate WP-PostRatingsWIDGET while have activated WP-PostRatings Plugin. So,when I activated WP-PostRatings Plugin, the Top Rated Posts started showing off on Sidebar and I thought it is due to WP-PostRatings Widget.
I just saw WP-PostRatings Widget was not activated.
Thanks Michael...Smart Work
1) So,if I already have "Top Rated Posts" showing up, I may not need WP-PostRatings Widget while I can leave the Plugin there?
2) My Sidebar also have default tag [<?php get_most_viewed('post', 5); ?>], which would pull "most viewed" posts. Do you know it is based on which Plugin ( e.g 'wordpress.com stats' plugin etc) ??