Re: Trying to get the virus
@AC1: yes, I've downloaded the GetWindows10-Web_Default_attr executable and ran it and gone through the first few screens. I'm at the Getting Updates screen and it has been checking for updates (0%) for the last three hours. Yes the internet connection is fine. Yes, the product ID is valid and the install has been validated.
@AC2: the problem that I seem to be having is that Windows Update just sits there for days not finding any updates, so I can't complete the first stage of the process you suggest. This install has been validated &c. Same appears to be happening while trying the Windows 10 installer (see reply to AC1)
Moral: if you want to avoid forced upgrade to Windows 10, just get a copy of Windows7 for refurbished PC.