I am in a solo FP office and use a peer to peer network. One of the computers is designated as the "server" and is not used as a desktop machine.
I have 4 desktop computers plus the "server" and am happy with the response and simplicity.
They are not cutting edge but no Pentium machines and have 4 GB of RAM or more and are connected through gigabit router.
I have wireless available but not using the laptop in the rooms yet.
Greg