I wanted to re-install Windows 7, what a mistake... first the update takes a core at 100% and just scanning for updates takes about 20h. There is 203 updates, it is a mess, there is updates for IE9, IE10, IE11 and multiples security updates for all browsers including IE8, then multiple .NET updates and others. Half of them fail to install, some rollback, after an update and a reboot it can find new updates, etc. All in all it takes a few days to install Win7.
So I took the MS tool, downloaded the 1511 ISO, wipe the partition and intalled a fresh Win10, after the install there was 3 updates, that's it, no bloatware, no forever to d/l and install update. In 20 minutes I was running and up-to-date.
I guess they have their reason to remove the 1511 ISO, certainly because you could install a fresh Win10 with a Win7 or Win8 key.
And do not worry /., I dual boot Mint 17.2 but need Windows for some programs like GPS update for instance.