Microsoft do indeed run IIS 5 on all of thier web sites, the backend of hotmail however is Free BSD (or open?), not only this Microsoft get an outside company (the name of ehioch escapes me) to host all of thier DNS machines and these run Unix (Linux I think). So, it's quite obvious that inspight of Redmonds claims they still try to sell a second rate OS that even they can't use properly!