A million hits a day ? I've deployed a .NET app that used to be serving more than 1 million hits an *hour*. The server is/was running in a dual-"cpu" vmware machine. Initially it was running mono under linux, but we had to re-deploy it on windows server and proper .net when the traffic was going insane (still virtualized though). Mono is very good, but ms still has the edge when you really need bleeding edge performance. Not so strange, considering that mono is still playing catchup. For applications that don't need that kind of throughput, linux+mono+nhibernate+postgresql/mysql and some kind of mvp framework is a truly beautiful and free solution. For development, an msdn subscription with visualstudio is a very good investment though. MonoDevelop is slowly getting there, but it's still quite far from being even comparable to visualstudio imnsho.