I haven't had any trouble with the free DivX codec, except trying to find it on the site. They really do try to push you to get one of the downloads that include "bonuses" and free software, or to pay, but they do have just the codec and player in there somewhere. I don't remember the file being more than a few MB's though. I have run Spybot and Adaware many times on my computer and haven't found anything yet that shouldn't be there.
ATI have a DivX player on their driver CD's for the recent Radeon cards (9500 and up I think), so that might help some people.
goates