I have been digging through all the posts here and can't find a solid, 100% confirmation on the following:
Can you install the Windows 8 Upgrade on a totally blank (ie new) hard drive? I keep seeing people post that they booted off the disc and were able to do a clean install, but they don't always indicate if there was an existing OS installed, which the upgrade disc would obviously see. Has anyone taken a totally empty/new drive with absolutely nothing on it prior to booting off the upgrade disc, no other drives with an OS that might be seen, and installed Windows 8 and have it activate properly? Microsoft supposedly has said a previous OS has to be installed/seen.
I've done it. I used the keys provided by Microsoft thru my Technet subscription and booted off a Windows 8 disc I burned. If you purchase an upgrade then you will need a an OS such as Windows 7 or Vista to install Win8; the full version will allow you to boot from the disc and perform a clean installation. Hope this helps.