i guess .NET has it's place, but it really isn't for the web, it is mainly used to be able to intermingle .NET applications (but yes, you can, and it will be used on the web, there are some neat features), like the newer office versions, other M$ products, etc... PHP is going to beat it hands down in the web department, since it is mainly a framework, don't confuse ASP with .NET either, they are totally different things, and yes there is ASP.NET, and that in itself is different than ASP
all in all, if you are worried that the webworld is gonna be swallowed up by .NET or ASP.NET, it isn't PHP will be around for a long time