Of course Microsoft know what the key is from.
Lets try it another way.
If a OEM Builders key come with a DVD and a Retail key come with a DVD how what is left.
Let me guess.
It's the people with a store bought system that is activated with a OEM/SLP key but also has a different OEM key on the Microsoft sticker but they have no DVD with Windows 7.
Out of the three users, OEM builders, Retail or store bought computers which one needs the Microsoft download.
OEM Builders don't need the download.
Retail don't need the download.
Only the people who have a store bought computer with a pre installed Windows 7 need the download. The Microsoft download must be meant for them. If that is true I don't understand why the Microsoft sticker key doesn't work.
I'm trying to verify that it doesn't work. The ones that fail might be getting the key from the wrong place.
This information might just come in hand for people that have store bought computers with Windows 7 pre installed.
I have no evil intentions with this information.