I originally had Windows 8 on this laptop, but I downgraded to Windows 7. I turned off the UEFI boot that was pre-enabled. I now am going to use the Windows 8 upgrade assistant to upgrade to Windows 8 from my Windows 7 installation. Will it bring issues installing it if UEFI is not enabled? Does Windows 8 need it to work? I just want to prevent any issues when upgrading.