If you would give us a link we could have a look, but basically all these SPAM-Filtering-GATEWAY tutorials are the same:
they usually are built around clamav as a virus scanner because its free and around spamassassin (althogu hI already saw one using another tool) the only difference there is, is that they are built different mailers - the tutorials from howtoforge usually use postfix as far as I have seen, while other s sometimes use qmail.
Also some tutorials use amavis...
Basically I think there is no better or worse system as long as clamav and SPamassassin are integrated. It is just: use what you understand - if one tutorial looks easier and understandable use that one, BUT if you want to use ispconfig I suggest you stick to the Perfekt Setup Guides which are available for a lot of OS-es.