Plugin to auto organize posts in categories?

I have a wordpress site with 1000 posts. All of the posts are in the “Uncategorized” category. I used this plugin to create bulk categories http://wordpress.org/extend/plugins/category-import/

But how to organize the posts in different categories? I have all post names in a .txt file. Is there a plugin that can allow me to assign each post to a certain category?

Thanks!