In reviewing the query and response about whether or not to use CAI, it seems that this is at the crux of what Tom is trying to say--or get us to understand. As far as we "down under" think (if I don't speak for all my colleagues here, they'll quickly let you know), the notion of CAI disappeared shortly after the meteorites removed the dinosaurs!
CAI is a manifestation of behaviorism, and it seems we have not only moved beyond that S-R world to cognitive approaches, but even further to the world of constructivism and building models of the world using the best tools.
So it is not a case of whether or not to use the technology, but whether the facilities provided by the technology will solve a particular instructional need. This means you not only need to know the technology, but what requires doing with your teaching and learning practices. The same can be said for using "canned" or "in-house" products. The answer lies in what you want to do. For example, if you were running a course specifically about the dangerous creatures of our world, then use Microsoft's "Dangerous Creatures" despite its rather difficult interface/navigation. Remember the old maxim "If it ain't broke, why fix it." Technology should only be used if it will do something better--its only the vendors and sales people who think technology is a solution.