Over the last couple of days I have been attempting to rehab a five year old laptop for my 11 year old son to use. As the system hard disk had been corrupted while sitting idle, making the restore partition useless, I had no option but to install a fresh copy from a downloaded Windows 7 Home Premium ISO.
I first started by going to the official Windows 7 ISO download page which required a key, so I inputted my OEM key and a message came back “The product key you entered appears to be for software pre-installed by the device manufacturer. Please contact the device manufacturer for software recovery options.” Obviously I already knew it’s a pre-installed/OEM key as I read it off the bottom of the laptop.
This meant that I had to find an alternative source for the Windows 7 ISO as Digital River no longer has direct downloads available, so we are left with using torrent sites. I used the following links; Windows 7 Home Premium (64bit) or Windows 7 Home Premium (32bit). Please note: I make no guarantee that these links are safe, use them at your own risk. I used the 64 bit link and it appears to be legitimate.
Now, install Windows as normal from the DVD or USB thumb-drive you created from the downloaded ISO, but when you reach the license key screen, click on “skip” which allows you to install Windows without a license key. Once you have completed the installation, installed your network/wireless drivers and connected to the Internet, simply open system properties and click the “Change Product Key” link.
You then input for OEM license key into the dialogue box that pops up and it checks with the Windows authentication server and it should, assuming it is a legitimate license key come back as genuine.
[Update: March, 18, 2016]: I also discovered that this method works for a Windows 10 clean install, instead of system properties, goto START » Settings » Activation » Change Product Key. It will accept your Windows 7, 8 or 8.1 key, no need to do an upgrade to Windows 10 from Windows 7, 8 or 8.1 anymore.