Best server environment for playing unity game?

Which combination of server setup is good to play unity games smoothly over 50,000 users at a time.


We establish connection between our php framework and db using “easy soft odbc driver”
Database : SQL 2008, scripting language : PHP

We are going to expand the no of users. which will be around 10,000 users. Here are our doubts

  1. Which os will be best windows or linux?
  2. Which server configuration will be best one?
  3. Which is the best server for this lamp or wamp or iss?

Thanks & Regards,