.NET 4 runtime. http://msdn.microsoft.com/en-us/netframework/aa569263 You'll need to figure out which version of it based on what your application does.

IIS, and again configured based on your application's needs.

Your application

SQL Server if you're using it

>Hello all,
>
>I have just converted my web application targeted to the .NET Framework version 4. What do I need to install on the server for the newly targeted application?
>
>As always, TIA
>
>Bob