I know in "I Am Legend," Will Smith had a nice shiny Mac Pro with which he did all his research.
All of the computers on the show "Scrubs" are macs with Sacred Heart Hospital logo stickers over the Apple.
I have no way of knowing, but my theory is most of the time, directors and such will just use Macs because movies are made on them, so they know they're better. There may be some kind of legal issue with this when Apple isn't involved if MS gets angry, and so they put the stickers on just to protect themselves?
Hmm.. I, too, noticed that about the Vaios on "Casino Royale." I'm used to everyone I like in movies using Macs, so when I saw James Bond pop out a Vaio I almost fell out of my chair. I'm not sure, because I've only seen it once, but I DO think it was running Linux though.... 😀