Which is the biggest upset in the World of Cricket?

As a few other users have suggested, India defeating West Indies in the 1983 World Cup final would have to be the biggest upset, all of the ones you have listed were interesting at the time but in the long term they counted for very little, they are just one minnow team winning one game then getting knocked out in the next round, none of them represented any kind of major improvement in form for that team.