ReCaptcha or Other Captcha on html form

Question

I'm trying to add captcha control to a form which is rendered using xml parser. (XML Parser gets all values from database and creates a include file with form which is appended at bottom of required page) This form makes a http post to a different page when submit button is clicked and then that page validates data and submits data to database.

I'm using recaptcha control

Issues: 1. XML is not able to parse .net control tag and i get xml parser error for tag . 2. How do i validate captcha on other page becos i cannot access recaptcha control to check isValid method.

Is there anyother captcha suitable for this kind of situation or how can i use recaptcha here?