I am running Windows 8 Pro RTM on my G74SX without any issues at this time. It has Been almost a month. My set up is as follows - NVidia 302.80-notebook-win8-64bit-international, ATKPackage Win7_64_Z100016, Touchpad by Sentelic_Win7_64_Z9135, USB3 Fresco_Win7_64_Z35300, Realtek HD Audio 64bit_Vista_Win7_Win8_R270, LifeFrame3 Win7_64_Z3029, ROG Gaming Mouse_Win7_32_Win_64_Z1000000, Cyberlink PowerDVD Ultra 12, PowerToGo 8 Platinum, PhotoDirector 3, iTunes 10.6.3.25, CCleaner 3.22, IZArc 4.16, Stardock Start8 Beta.9 along with Office 2013.
Hope this helps
I am still a Happy and Satisfied G74 Owner!