I have one with a bios mod with Windows 7 and one legitimate one with bios slic. Both received the notification to upgrade. Not sure that means it will be okay with the mod. Just means that the hardware is compatible.
Probably that why. i have a legit windows 7 key, so will try to install it on a vm tonight and see if it will pop up with the windows upgrade.
I have one system set up with das loader and it has the little white window and I got an email saying I had a reserved copy ! I had another system set up with das loader that I upgraded to win 8 for I think it was about $40 and got media center for free it now has 8.1 on it and has a windows 10 reserved copy, so far it seems like both will work but we shall see when it happens