Let me pose a hypothetical scenario: let's say someone put spyware on the web, but with some modifications which made it virtually impossible to suspect: let's say it pretended to be from your software maker, Microsoft. In fact, it has the word "Genuine" in the title. And let's say that it sets itself up so that it cannot be uninstalled, and so that it must be running in order for you to download important security updates. Sound scary? It sure does to me.
Actually, this software does exist. It's called Windows Genuine Advantage. Well, you might be saying, what a smart idea those spyware-makers had, pretending to be Microsoft. There's one catch: it isn't pretending to be Microsoft. It is Microsoft. Our good friend Bill Gates has information on any Windows user who has updated in the past month.
It's things like this that make me glad I switched to Linux: I can live without the iTunes Music Store knowing that my web history (which websites I visited and when) is not being read by the company which makes my OS and which I should supposedly trust.