I would think that most mainboard vendor's will take the hybrid (EFI - BIOS) approach as they can't be sure the person who purchases their MB will have the necessity to boot Linux (or some other OS) along with Vista.
I would guess this because I am assuming a strictly EFI approach (at least currently) will not allow Linux to boot. Is this assumption correct?
With regard to a virus and the ASLR mechanism: Wouldn't it be possible for a virus to try each of the 256 locations looking for the function address it requires?
Also, with regard to the UAC, many users of Vista will not understand what the UAC message is actually attempting to convey and in some cases they will just click Continue. Do you have any words of wisdom as to how to instruct these people how to handle the
UAC events given this lack of understanding?