The 'full' version is now Windows 8 System Builder. The Upgrade/Full confused a lot of people, thinking that the 'full' version had more functionality or features, when it was just a licensing difference.
I don't think the System Builder version is available for pre-order yet.
The only reason you would need System Builder is if you are building a new PC yourself, or have a version older than XP.
XP-Vista-7 users can use the one provide on Amazon's side that is the non-System Builder version.
(PS If you are building your own PC, most of the time people are retiring an old computer and can migrate that license under the new Windows 8 upgrade rules. If you are 'serious' about building PCs like professionally, you should be buying wholesale OEM copies that are far cheaper or buying via licensing. You can also use 'deals' through Microsoft for private use and testing on various Partner programs.)
I actually sold my own full retail Windows 7 Home Premium for about £65 on ebay and have been running the RP/CP on my self-built desktop since. Consequently, if I went for the upgrade option I'd have to look at buying a full XP license on ebay or something to that effect and then upgrading to Win8. It all just seem a bit arse-about-face whenever you have to reinstall from afresh (or after upgrading the primary hard disk for example), as I'm under the impression one would have to reinstall the previous OS and then perform and upgrade from that. MESSY.
You actually can to a clean install using the upgrade version (at least you could with Win7, hopefully they continue to allow that considering it results in a more stable installation). Also, keep in mind that technically you can only resell the retail version of Windows. The OEM license that comes as a sticker on your computer is only valid on that computer. If you buy it from someone else it isn't technically legal.
You can still do a clean install from an upgrade copy.
I just wanted to continue this conversion from the front page regarding Windows 8 Upgrade.
What occurs in a worst case scenario? I.e. a hard disk failure and you wanted to reinstall Windows 8 afresh? I assume the fresh install utilising an upgrade license required for you to have reinstalled the previous operating system and then upgraded from that again?
I'm just trying to work out the most sensible and cost effective path to take!