Small Office Server - Processor Options

A customer on a tight budget is upgrading their network of < 5 computers. Dell low end servers give several option of processors the lowest cost are Intel Core i3 ( e.g. Intel® Core™ i3-3220 Processor, 3.30GHz, 3MB Cache, 2C/4T, 55W ) then at a higher cost Xeon Processors (e.g. Intel® Xeon® Processor E3-1240v2, 3.40 GHz, 8MB Cache, Turbo, 4C/8T, 69W  ) etc.

What advantages would there be for a very small office network only using the server for storing files, printing and providing centralised  user authentication to use a Xenon processor rather than Core i3 ?

Thanks

John