Pro Recent Comments Widget plugin.You have choice to customize your most recent comments.
- You have choice to specific post comments only show.
- exclude any post comments.
- set maximum no of comments.
More detail : http://socialcms.wordpress.com/
How to only select post comments?
In pro recent comments section post ids section add post id which post comment you want
How to exclude comments given post id?
In pro recent comments section exclude post id section add post id which post comment you want to exclude