Chicken or the egg

Hello,

I am using Captcha on a feedback form and have a dilemma:
1. I have several form fields I require the user to fill in before they submit feedback
2. As a result, I use javascript to validate the fields

Here is my javascript call:
                 <form ACTION="<%=MM_editAction%>" METHOD="POST" name="Feedback" id="Feedback" onSubmit="YY_checkform('Feedback','Name','#q','0','Name is required!','E-Mail','#S','2','E-Mail is required!','securityCode','#q','0','Security Code is required!');return document.MM_returnValue">
 

How can incorporate a Captcha call similar to the example listed below?
<form action="captcha_result.asp" method="post" name="form1" id="form1">

Regards,
Bob