Spam Users/Spam Posts

[Moved from Your WordPress which is NOT a support forum.]

I have tons of spam users registering everyday and are posting naughty things. My website allows authors to post as a social network. But its getting annoying to delete all spam users and posts. I have this plugin http://confidenttechnologies.com/products/confident-captcha
and used every plugin, but spam users still find their way into my website. How can I block them..