Mourinho probably will win more than Sir Alex, I don't doubt that, he is an incredible manager, one of the greatest of all time, but you can't compare him to Sir Alex, and to any United fan, Sir Alex will always be the greatest manager in history.
Fergie has been largely a one club man, taking a single team to becoming the greatest sports brand in the world, a billion pound plus club, year after year winning trophy after trophy, building new teams that can challenge the greatest continuously, Sir Alex has built a never say die attitude into all his teams, he takes no nonsense from anyone, he does it his way always.
Mourinho, well what he has achieved is unbelievable, the things he did at Porto were just insane, and then Chelsea he was perhaps not as ridiculously good, but he won it all except for the champions league, and then Inter Milan, to do what he did, a treble, again... and now Real Madrid are going to top the Spanish league, and potentially have a champions league final ahead of them, who could of seen Real topping Barca? I couldn't, but Mourinho has done it.
Personally I would love to see if Mourinho can achieve the success he's had at club level, at international level, he's a short term manager I know, so I'd be very intrigued to see him manager say England for a 2-4 years and see if he can win something.