Adding Captcha To A Form?

I'd like to add Captcha to a feedback form, but can't seem to figure out how to do it.
I've searched the web and there are many site that say they show you how to do it, but somehow I always get stuck...

It would be great if someone could help me out.

<form method="post" action="process.php">
  <table width="87%">
     <tr>
          <td width="23%"><span class="style4">Name:</span></td>
          <td width="77%"><input name="name" type="text" size="30" maxlength="50"></td>
     </tr>
	 <tr>
       <td><span class="style4">Email:</span></td>
       <td><input name="email" type="text" size="30" maxlength="250"></td>
	   </tr>
	 <tr>
          <td><span class="style4">URL:</span></td>
          <td><input name="url" type="text" size="30" maxlength="150"></td>
     </tr>
     <tr>
       <td colspan="2"></td>
       </tr>
     <tr>
       <td colspan="2"><span class="style4">Testimonial:</span></td>
       </tr>
     <tr>
          <td>:</td>
          <td><textarea rows="7" cols="30" name="testimonial"></textarea></td>
     </tr>
     <tr>
          <td></td>
          <td><input type="submit" value="Submit"></td>
     </tr>
</table>
</form>

Code (markup):

 

Use this http://recaptcha.net/

 

Did that work for you, or do you need more help?

Here is an alternative: drupal.org/project/captcha

 

I am using the reCaptcha WordPress plugin, easy as 1-2-3 to install and configure. Deters the bots and spammers, nice. I use reCaptcha for non-WordPress sites too with excellent results.

 

Yup recaptcha is today's solution.

 

recaptcha is nice way to implement .... you can also write your own code in php to implement captcha

 

recaptcha works with domain licenses, I need something 'universal'