Not wishing to appear rude but, if your friend is going to run a SUCCESSFUL internet cafe, he needs to have sufficient knowldge and expertise to be able to answer the questions that you pose here himself.
Why should he want to install a second copy of the operating system he has already there? Just because it may be a corporate edition doesn't make it any better. If it's a problem with activation then the version that is installed will have already been activated. You can't (legitimately) take it out and use it elsewhere.
Or have I misunderstood everything?