Should I choose Linux or Windows Server>

I am working at an organisation that did not have any IT infrastructure so I am setting up new systems. I have started with a LAN and I am now going to put a server. I want to deploy just email, web, file and print services for now as well as Internet sharing. I am in a dilemna. Should I go and put a Linux server or Windows since I do not want to incur any more costs such as Exchange etc.