well, apple products are what customs looks for the most. although my understanding is they finally at least allow you now to bring one computer across as part of your personal duty or whatever so if you bought a new macbook outside i think you can bring it in without paying duty. it will be much cheaper to buy one outside the country, and you will likely not find the latest and greatest model here.
I wouldn't worry about bringing in a new computer.
I've never been asked to show my computers. But just in case, when I have a new one, I set it up and load some photos before arriving so that it looks like I've been using it. Bringing in a new machine, unwrapped and unopened, would be tempting fate.