We currently have a webserver with .NET 2.0 SP2, .NET 3.0 SP2 and .NET 3.5 SP1 installed on it. The sites are running in ASP.NET version 2.0.50727. My question is, if we install .NET 4.0 on this same webserver, will it effect the websites? Is installing 4.0 similar, or the same, to installing 3.5? When we installed 3.5, the sites weren't negatively effected. Please let me know if it is safe to install 4.0 on this webserver without breaking the sites which currently reside there.