Joe,
From my experience, and this may be OEM specialized, a Windows 8 secure boot will ignore other boot media. For instance, Secure Boot requires a uEFI boot. If something is trying to boot that is not UEFI and certified, it will not be allowed to boot.
You are supposed to be able to turn off Secure Boot, if you so desire, and I can, the option is in the bios. I don't know if the link kemical provided discusses this, but for Windows 8, there is Secure Boot and Trusted Boot. I suppose one is during boot, and one is when starting the OS. Apple has been using this for a while, so if you only use Windows 8, it won't be a problem.