Apple rolled out a campaign in 2006 that featured a bespectacled, slightly nerdish actor (John Hodgman) representing Windows, and a young, cool, hip actor (Justin Long) representing the Mac. The ads present the Windows character as problem-prone and constantly exasperated, and the Mac character as always cool and collected - but thanks to the likable actors, without seeming mean-spirited and overtly negative. I personally like the "Cancel or allow" ad, which pokes fun at Windows Vista's sometimes annoying security model.