Just got my replacement unit and upgraded it to windows ten. The product key that came with this desktop didn't work, but the sticker on the case had a key that worked. Just follow these directions:
https://www.laptopmag.com/articles/upgrade-to-windows-10-free and once windows ten is installed go to activation and it lets you put in the key from the sticker. Additionally, to get my ethernet to work I had to install the Intel drivers located here:
https://downloadcenter.intel.com/do...k-Adapter-Driver-for-Windows-7-?product=41676 just thought I'd share in case anyone is getting this desktop for a hackintosh and/or dual boot system. It runs much better on Windows 10 imho than Windows 7. I'll be working through the guide on creating my Sierra boot disk next week. Thanks again for finding this deal - for the price that Apple quoted me to fix my MBP that was three months out of warranty, I was able to get a great monitor and desktop that will run OSX!
PS: One of the legs on the keyboard was missing on my second unit, so be sure to check everything over when you receive this desktop. This seller seems to have problems with quality on little stuff like this, but my machine has been running perfectly. I'm trying to talk them into giving me a partial refund as I was going to get a different keyboard anyways.