I've found Mollom http://www.mollom.com http://www.mollom.com very effective at preventing spam. It was super easy to add as I was already using Drupal. But it

I've found Mollom http://www.mollom.com http://www.mollom.com very effective at preventing spam. It was super easy to add as I was already using Drupal. But it will be more work to add to pligg. Maybe it would be less work to convert to using drupal/drigg http://www.drigg-code.org http://www.drigg-code.org ?