[Wanted] captcha in php

I need a simple job doing - a captcha for directory submissions at the Platinax directory, ie:

http://www.platinax.co.uk/directory/add/2/1.php

It's simply to stop autosubmissions by bots.

I notice a number of companies keep targeting the directory, even though it's a paid for directory, and a captcha should help prevent the junk being submitted.

One for Brian's business blog would be nice as well - tried a plugin but didn't work.

In both cases, just looking for something simple, probably in PHP.

Please send a reply to enquires at britecorp.co.uk

 

I've used this one before:

http://www.phpclasses.org/browse/file/4146.html

but there are others out here:

http://www.google.com/search?source...GGLD,GGLD:2004-46,GGLD:en&q=php+captcha+class