There are the advantages of .NET, asp and so on but I think linux is better generally depends on the host really. Because linux is more secure standard built on unix foundations plus linux hosting is cheaper generally as the hosting company doesn't have to pay to have linux on there server(with the exception of red hat linux) yet they do with windows. At the end of the day its all about preference and the quality of the host you can't compare a crap linux host to a fantastic windows host as regardless of server os the fantastic host will be better.