content: i think the issue is that ppl bough either an ASUS MB, or a pre-built computer with the ASUS MB, and proceeded to install windows 7, without looking or caring about the BIOS setting.  Then MS pushed out an update to windows 7 that triggered secureboot.  So i don't think its that OEMs enabled secureboot for windows 7, but rather they made their MB secureboot compatible.