Hi Sueellen,
I'm currently in University at the moment (not doing anything regarding computers), but just thought I'd add my tuppence worth. Its really surprised me over my 4 years here just how many people have realised that the course they picked isn't the one for them, and either transferred to a different course/college. As far as I'm aware most of the courses in DIT are all degree level, while in Tallaght IT theyre usually step by step (cert after 2yrs + diploma after 3yrs + degree after 4/5yrs). If your son really isn't sure about the course, maybe the IT step-by-step route is the best for him, he could change courses after 2 years and still have a qualification in computers. If he leaves DIT after two years he has nothing. Please bear in mind that I have absolutely no experience of any computer science course, nor any DIT or Tallaght IT course, this is just general experience I've gained from being through the third level system.