If I need to provide any application architect then based upon some requirement, I can suggest Distributed or Service oriented architect. Like if it need to integrate with multiple system then I can suggest distributed architect and integrate it with third party systems through WCF/ Web services. But if client ask me to provide what will be system requirements for deployment then I am not sure what should be server configuration that can support which amount of load.
May be I am asking very subjective query but I want to know if client says I need to develop a system which 2000 active users and out of that 500 are transactional users. It also need to integrate with 10 more system which should be real time integration. So here I can suggest web server, app server and database server at physical layer. But how much web server, app server need to deploy and what should be configuration (RAM, Processor etc.)? How we take these type of decision?