Moodle can run on most software stacks and would recommend using what you are familiar with. It will be much harder to tweak a linux stack if you have a heavy windows background, and vice versa. Your budget will determine how redundant and performant you can make the system. I've seen quite a bit of warnings within the forums about using virtualization but in my experience virtualization can perform just as well and better in certain circumstances when considering stability, performance, scalability, etc. Go with what you know.