You can't because there isn't.
Edit: for clarificatiohn
You: You can download a windows OS cd from the internet
Me: No you can't
You: Yes you can
Me: Find me a MS statment or sentance in the EULA saying you can
You: I will not
Me: You can't because it doesn't exist in the EULA or MS statment. No Permission
Edit: for clarificatiohn
You: You can download a windows OS cd from the internet
Me: No you can't
You: Yes you can
Me: Find me a MS statment or sentance in the EULA saying you can
You: I will not
Me: You can't because it doesn't exist in the EULA or MS statment. No Permission