I hope I don't get in trouble for reposting this from my Asus S56 teardown thread, but looking at the titles of some of the other posts, it looks like many other ASUS owners who bought a new Windows 8 Certified notebook are having a hell of a time in installing Windows 8 Professional over the Windows 8 Standard OEM that came with their new notebook / laptop / ultrabook.
With Windows 8 now out, prebuilt computers and notebooks that are deemed "Windows 8 Certified" adhere to certain security protocols on the BIOS level that make installing an OS other than what came with the machine increasingly difficult.