There are no two ways about it: properly vetted open source is more robust, easier to install and manage, and better supported. Our servers are generally Linux based platforms comprising Postgres or MySQL, an Apache web server, and a high level programming language. The low cost of the server and the absence of recurring licensing costs are just added benefits.
While most everyday users work with proprietary, friendly desktops and laptops running Windows or Mac OS, they often rely on stable Linux servers for access to organizational and internet data. Many large online services, like Google and Yahoo, run on Linux.