Captcha

I have a simple e-mail form that checks for bots, exploits, spam words, ect.

Anyone know how to add a captcha to work with my form?

 

Free php captcha with installation details. Includes comment script and form >> email if you need those too.

 

The official one is good, quite alot of big softwares use it.

http://www.captcha.net/

 

Whatever you decide to use, make sure you stay on top of the latest captcha bypass methods. They come out about as fast as new captchas do.

 

I just cant work out where to add the code from Free php captcha :-(

here's the part i want to add captcha too...


// Add and Insert Functions
///////////////////////////

else if($ax=="add")
{
$date_added=date($date_format);
?>
<p><br>
<img border="0" src="/images/smallbanner1.gif" width="281" height="36"><br>
<br>
&nbsp;</p>
<p class="bodylgbold">Add a Link</p>
<p class="bodysm"> &gt; <a href="<?php echo $PHP_SELF; ?>">Home</a> &gt; Add a Link</p>
<p class="bodymd">All Fields are required for link submission - If you can't
find a category then please <a href="email.php">Contact us</a> and we'll happily
add one!</p>
<form action="<?php echo $PHP_SELF; ?>?ax=insert" method="post" id="form" onsubmit="return validate_add();">
<table border="0" width="100%" cellspacing="2" cellpadding="0">



<tr>
<td class="bodymd"><span style="color:#FF0000;">*</span>Category:<br />
<select name="cat_id">
<option value="">Select a Category</option>
<?php



$result=MySQLQuery("select * from links_cat where id !=0 order by name",$QueryError_Email,$QueryError_Browser);
while($row=mysql_fetch_array($result))
{
$cat_id=$row["id"];
$cat_name=$row["name"];
echo "<option value=\"$cat_id\"> $cat_name</option>";
}
?>
</select>
</td>
</tr>
<tr><td class="bodymd">Name Of Business Or Resource<span style="color:#FF0000;">*</span>:<br /><input name="name" type="text" size="60"/></td></tr>
<tr>
<td class="bodymd">Description<span style="color:#FF0000;">* <font color="#000000">(Max
255 characters)</font></span><font color="#000000">:</font><br />
<textarea name="dsc" rows="3" cols="40"></textarea></td></tr>
<tr><td class="bodymd">Website URL (If known)</span>:<br /><input name="url" type="text" value="http://" size="60"/></td></tr>
<?php if($image_enabled=="yes"){ ?>
<tr>
<td class="bodymd">Image URL (Optional) (Images size 125x100 pixels)<br />
<input type="text" name="image" size="60" value="<?php echo $image; ?>" maxlength="100"/></td></tr>
<?php } ?>
<tr><td class="bodymd"> Email Address:<br /><input type="text" name="email" size="50"/></td></tr>
<tr><td class="bodymd"> Password:<br /><input type="password" name="password" size="10"/></td></tr>
<tr><td class="bodymd"><span style="color:#FF0000;">*</span> - indicates required field</td></tr>
<tr><td><input type="hidden" name="date_added" value="<?php echo $date_added; ?>"/><input type="submit" name="submit" value="Add Link"/></td></tr>
</table>

any ideas anyone ?