Actually, I didn't like the I'm a Mac ads as good as the newer ones. Mostly because the newer ones concentrate more on just showing what you can do on the hardware, and how easy it is. This is instead of the even more smug "I'm a Mac" commercials. They just seemed more like they concentrated more on "Making fun of the other guy" in them. So the attitude of the Mac guy seemed a bit irritable. Though, the "I'm a PC guy" was always quite funny. He, in a way, made those commercials. But I think it speaks in more volume to just show how this device simply allows you to do "this" easily instead of making them talk down the other guy.
That's what I think are the more effective commercials, though yes, without the "I'm a PC" guy's humor.