I downloaded an .iso version of Windows 8.1 from dreamspark (so it's a legit copy). At the moment I have Vista installed on one HDD, and I want to install 8.1 on another.
However when I go to boot from disk, the purple Windows 8 symbol appears, and then the computer proceeds to boot back into vista. Why would this happen? Is windows 8.1 only an upgrade perhaps?
edit I've just noticed this error message appears for a split second before it boots to Vista: