Plus, I would strongly suggest not using Windows for a business-critical server. Most Windows admins build a reboot into their standard administration protocols. To me, that's a red flag.
This may have been true five years ago (and don't I remember those early versions of NT 4 with horror ...) but I don't believe it is an accurate representation these days. The project I am currently working is implementing an entirely Windows based Billing system for a multinational company with thirteen operating companies in 9 different countries, this kind of thing is quite costly and failure is generally not considered to be particularly career enhancing, so understandably the people making the decisions are extremely cautious when choosing the software and the platform it is to run on. Some very intelligent people have bet their jobs on the reliability of the application. This system achieves in excess of 99.5% availability across eight or more windows servers.
Windows might not be suitable for every application but to suggest that is not suitable for a "business-critical server" is palpable nonsense.