>>This may not be helpful, and I am not an attorney. but there is no way to legally change
>>an EULA once issued. IOW if you purchased the software under terms X,Y, and Z, it is not
>>legally permissible for MS to change those terms to your detriment.
>
>That is correct. However, every time you see a new EULA pop up with "Accept" and "Decline" options, they are renegotiating. If you click accept, you're bound to the new terms.

I am not a lawyer either but from what I remember of a business law class in college one could probably contest that. One of the four elements of a legal contract is "consideration," which means both sides must give something and receive something. Getting to keep what you already have is not receiving something (the classic example being "you get to keep your job").