I would suggest paying for the pro, it's cheap and very worth it. You can insert the form into articles (something that is a hassle with other extensions) and you have the option for Captcha. I had an extension before that gave us heaps of spam.
This is easy to use, and the support team is excellent. Don't waste your time with another extension, this one is worth the money. I promise the others will give you a splitting headache.