I have several CGI based forms on my website, some quite simple (i.e. contact form) and some more complicated. Recently, they have been compromised by SPAMBOTS.

While looking for the ways to protect my forms, I've found a CAPTCHA for PERL script http://bumblebeeware.com/captcha/, but having difficulties to install a working and secure solution (although the demo is working well on my server).

Any advise on the ways to protect the forms and any help would be much appreciated.