Did you boot the win 8 DVD in UEFI? I have a G74S and it just works. Before enable UEFI in BIOS try to press bottom to show boot menu as son as asus logo appear. There`ll be options to boot by de DVD one with UEFI chose that one. Since your drive is MBR formatted the windows 8 install will say it`s not possible to use that partition. You have then to delete all partitions and create a new one. Actually the win 8 will create tow more partition by his on to proper work, and or drive will be GPT formatted. If I cold be of some help just ask sorry for the English I'm Brazilian.