I have to disagree with you on this. Apple would never have released the iPad if they thought it would cannibalize either iPhone profits or notebook profits. I am sure their analysis found that while it would steal some sales of other products, overall they would make a larger profit by releasing it. This is why it is at the price point it is at. Between notebooks and iPhones.
Also, most people who are buying the iPad already own a mac and an iPhone and aren't using it as a replacement for those, but rather to supplement them. Apple knew this. I think the only thing they didn't predict that people would jump on the iPad bandwagon so fast.
But your analysis of Microsoft seems accurate. They have issues with their units working together.
Apple's Strength: It Isn't Scared of Apple