CAPTCHA Server Control for ASP.NET - protecting from spam

Looking to protect your public facing web sites from automated submission/spam - leverage CAPTCHA Server Controls readily availbale for ASP.NET -

ASP.NET captcha implementation - http://www.codeproject.com/KB/custom-controls/CaptchaControl.aspx

Telerik Captcha - www.telerik.com/products/aspnet-ajax/captcha.aspx

Google's ReCaptcha - https://www.google.com/recaptcha

-Dipesh