That would be a waste of money. More than a few users and MS screws you on the licensing. Even getting the OEM discount price at Dell when you buy a server it's $900 for 5 clients, $3,700 for 25 clients. For OS X it's $500 for 10 clients, $1,000 for unlimited clients (retail, not when purchased with hardware). Linux is free, unless you pay for support.
It's not hard to run 50 users on a modern high-speed 1U these days, and with Windows the licenses may end up costing you a large percentage of your total purchase price.
It's not hard to run 50 users on a modern high-speed 1U these days, and with Windows the licenses may end up costing you a large percentage of your total purchase price.
If OS X can provide directory and authentication services that are worth that, and can get the application developers to support that platform, they'll be worth considering.