This is what I'm doing for my gaming PC. Installed Win 8 fresh on a clean drive with drivers installed then patch it all the way to 8.1. I then make a image of the clean install that will be spanned on DVD and on a backup drive.
When Windows 10 arrives I will take that Win 8.1 image and on a clean drive I'll restore the Win 8.1 then upgrade that to Win 10 and make a new image of it and span to DVD's as well plus on a backup drive.
Along with that I have a Virtual of Win 8.1 in Hyper V clean installs. I'm going to upgrade a copy of 8.1 to 10. Might as well emulate it if I don't want it as my main system OS like I do Linux. I love Lunix but I don't like it as my main OS. Software to image your PC can be found here. http://clonezilla.org/ Just use this serial number.. you will have to convert to Decimal first. Not allowed to post serials here.
1100110100110010111