Just an added note that I suspect some of these notices are simply part of the automatic billing system that supports not only OneCare, but also other Windows Live services like Hotmail Premium and others. It's probably nearly impossible to fully disable these messages for OneCare and still leave those for other products functioning.
To deal with this they seem to be sending lots of the other special notices stating that OneCare is End-Of-Life and indicated you need to select another protection application. Though this may be confusing, at least you are receiving the message that something is changing and if not sure how to proceed have taken the time to come here and ask.
Rob