[magduf]

My answer is still the same, and actually assumed that. No one is really "greenfield": everyone is already invested in some technology to some extent. If your organization is already invested in MS technologies, your managers only know MS, and your developers only know MS/.NET/etc., then the choice is pretty obvious: MS SQL Server. Switching to Linux/PostgreSQL would be a sea change for an organization like that (even though, IMO, it would be better in the long run).

Similarly, if your organization is already a Linux-based one, running Linux servers for everything, adopting SQL Server would be a huge PITA and would likely be laughed out of the room if suggested.