Then I found JComments by JoomlaTune. Perfect! Exactly what I wanted for my site, and very painless installation. Here is a little bit of information about JComments:

The JComments allows to website visitors to leave comments to any published materials. It provides the flexible system of access rights settings, wide possibilities of custom view setting, uses the AJAX technology and provides many other features.

Main features

• Allows turning on/off the comment system for categories, single material as well as for static material.
• Allows automatically to publish the comments for existent users' groups.
• Setup the edit/delete rights for existent users' groups.
• The spambots and flood protection.
• Informs the administrator about new comments.
• Allows users to be informed about new comments.
• Possibility to edit comments from front-end.
• Possibility to display comments page by page and custom view of page numbers position.
• Setup the comments display order. (the last comment in the beginning or otherwise in the end of the list)
• Supports smiles, allows to customize their display order in the list, and allows to assign symbol combination, which can be converted into smiles.
• Supports the BBCode with possibility to setup the access rights to tags for different users' groups.
• Supports "hot" keys to send comments or insert BBCode tags.
• Usage of AJAX technology allows to add, delete and edit comments without page reloading.
• Allows to show the comment adding rules to some users' groups.
• Supports RSS-feeds for comments on any material or for all comments.
• Supports the template system to customize the view.
• Possibility to show and check the "Website address" and "Email" fields in edit form.
• A simple filter of unquotable words.
• Multilingual support (russian, ukrainian, belorussian, bulgarian, english, german, latish, italian, turkish).
• Supports the search within comments by help of search mambot.

Additional features

• Automatically removes repeated line breaks.
• Setup the minimum/maximum username length.
• Possibility to forbid usage of some user logins.
• Possibility to setup the maximum allowed comments length.
• Definition of the external links in comments text.
• Check the duplicate presence while adding comment.
• Built-in protection of e-mail addresses in comments from spambots.
• The technology to avoid the design break by very long links or words.
• Allows automatically to remove nested quoting in comment.
• Allows automatically to delete prohibited or unsupported BBCode tags in comments.

More information about JComments, or JoomlaTune