The suggestion made in that other thread (performing a regex check against the term "www" and dropping the comment if true, otherwise allowing the comment) is the most silliest suggestion that I have ever come across in many years. It is totally nonsensical, as it will allow
http://example.com/this-could-be-a-spam-link/ and disallow an innoncent text like "
I enjoy surfing the www". Performing a check against the protocol "http://" is silly as well - as a spam link can be forged otherwise. Forget those suggestions, they are silly and won't help you at all, as you'd need to be a coder to apply it. If you were a coder, you wouldn't have to ask where to apply it. Use one of the existing methods to fight spam using Captcha (or reCaptcha as Joe already suggested) or Akismet (search the board for those terms) or (even better) upgrade to cpg1.5.x, as that version has got anti-spam mechanisms out of the box (Phill already told you so). I'm pretty sure that new comments are not being processed by make_clickable in recent versions, so I can't see the point. If you think that applying code changes to the core is a better solution, go ahead and do that, but then don't ask for our opinion in the first place. The question where the code that you need to change resides at shows that you don't have the skills to perform the needed changes anyway. If you are a coder, take a look at make_clickable and turn the processing of comments off in this aspect.