Keeping Users In Check

I'm trying to find out if there is a way we can prevent users from creating/storing/copying/pasting files onto the root directory. This is because i want to prevent anything from writing itself there other than the system itself. Because most of the autorun viruses etc copies itself there. There are numerous viruses out there which does this. And at this present time, although majority of the anti-viruses can track them, we might never know if another way to circumvent anti-viruses watch and defenses can be formulated. This is the basis i'm looking for this specific way to block users from storing files on root drives. And yes i am aware that natively UAC does watch over these places which means without elevated privs, nothing can be stored there. But what good is security if the home owners welcome thieves in disguises?