I'm now using Ubuntu and Windows 10, but more as an experiment, I used a spare hard drive to do a fresh install of Windows 7 Home Premium. The install and activation went smoothly. But the update process was incredible. I had set it to install updates automatically and after checking for updates failed (as I expected) I rebooted the PC and went to bed. In the morning around 9 am it said installing update 131 of 208. The updates took until 1 pm until they had all installed and then I found over a 100 failures. Some of those fails had probably been fixed by the 100 or more updates that had installed. By my estimate the updates had taken around 8 hours just to install. A bit of googling around told me that 8 hours was quite common for a fresh install of Windows 7.
The forums say that Microsoft are probably giving priority to Windows 10 on their servers, with some people saying it is deliberately slowing down Win 7 updates to force people to Windows 10.
As a comparison the updates for Ubuntu 14.04 LTS are only a few hundred megabytes, and install in around 20 minutes!