Making a PHP form SPAM proof

Hi, I have a php form, that when its filled in and submitted the information is put in to a database and waits for me to approve the details. At the moment there is no SPAM protection, and im getting flooded with SPAM from the form. So I need something building in to the form to stop the automatic spammers, something like a unique number, or one of there picture code things that needs to be validated before the form is submitted. See the form at [login to view URL], I have also attched the form to this posting. Thanks Lee