I just started a networking admin position at a school/church where I manage a network of around 80 nodes. For the past four years, they have been a peer-to-peer network. I am recommending purchasing server grade hardware to host a win2003 domain controller so I can manage the server centrally. My two supervisors are asking why a domain is so important or even right for them. Reasons like "p2p is for 10 or less computers" and "it helps me manage and secure the network" just doesn't mean anything to them. I have a meeting in the morning to present my case to show them the yearly budget should be better spent on a domain controller over 10 new laptops to add to the p2p network.
I found this blog entry that I have found to be helpful: http://blogs.ittoolbox.com/networking/smart/archives/intro-the-peertopeer-network-7106
Any additional hard-hitting points or considerations you think would be very important for my sups to hear, please let me know.