No, Windows 8 Enterprise upgrades can only be done from the Windows 8 Enterprise ISO itself - this makes sense now. The upgrade advisor can only upgrade you to retail copies of Windows, Windows 8 or Windows 8 Professional. The Enterprise ISO has the upgrade advisor on it, hence my confusion . If you can get a Win8 Enterprise ISO from your IT staff (or if you have a TechNet or MSDN subscription, you can get it from there too), you can upgrade your installation. You can't do that with the upgrade advisor .

Somehow I missed that part in your first post!!!!!! My apologies for dragging this out unnecessarily!