If you have a new Windows 8 certified motherboard (such as the Asus P8Z77-M Pro), the following blog has some useful instructions on how you can enable the Secure Boot feature of Windows 8.

Link: derek858.blogspot.co.uk/2012/08/how-to-configure-windows-8server-2012.html

Secure Boot is required for all retail Windows 8 computers that get Microsoft's stamp of approval. Individually sold motherboards for built-it-yourself PCs can also implement secure boot. To support secure boot the BIOS must be UEFI based, and also specifically support the Windows 8 secure boot extensions and embedded Microsoft certificates. A TPM (trusted platform module) is NOT required for secure boot or ELAM.

Configuring Windows 8 Secure Boot
New security features in Windows always pique my interest, and secure boot was no exception. So this weekend I built myself a new PC, which I specifically pieced together to support Windows 8 secure boot. After extensive motherboard research, I ended up with an Asus P8Z77-M Pro motherboard, which is Windows 8 ready. Flashing it with the latest BIOS enabled the Windows 8 secure boot UEFI feature. You can check out other Asus Windows 8 motherboards here.

Now the tricky part was figuring out exactly how to install Windows 8 to leverage the new UEFI secure boot extensions of my motherboard. After a lot of re-installs and testing, the process is actually not that difficult and there's even a powershell command to tell you if secure boot is enabled and functioning so you aren't guessing whether the process worked or not.

The instructions are specific to my motherboard and firmware revision, so your screens and features may not be the same and require some tweaking to get the right combination of settings to work.