RuntimeEnvironment Class

using System;
using System.Reflection;
using System.Runtime.InteropServices;

public sealed class App 
{
    static void Main() 
    {       
        // Show whether the EXE assembly was loaded from the GAC or from a private subdirectory.
        Console.WriteLine("Did the {0} assembly load from the GAC? {1}",
           Assembly.GetExecutingAssembly(),
           RuntimeEnvironment.FromGlobalAccessCache(Assembly.GetExecutingAssembly()));

        // Show the path where the CLR was loaded from.
        Console.WriteLine("Runtime directory: {0}", RuntimeEnvironment.GetRuntimeDirectory());

        // Show the CLR's version number.
        Console.WriteLine("System version: {0}", RuntimeEnvironment.GetSystemVersion());

        // Show the path of the machine's configuration file.
        Console.WriteLine("System configuration file: {0}", RuntimeEnvironment.SystemConfigurationFile);
    }
}

// This code produces the following output.
//
// Did the RuntimeEnvironment, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null
// assembly load from the GAC? False
// Runtime directory: C:\WINDOWS\Microsoft.NET\Framework\v2.0.40607\
// System version: v2.0.40607
// System configuration file: C:\WINDOWS\Microsoft.NET\Framework\v2.0.40607\config\
// machine.config