How to make VS 2008 to register a C# COM DLL

To make C# create and register the typelibrary go to
Project/Properties/Build tick Register for COM interop. (Reccomended Choice)

Otherwise you need to use REGASM (see here  for the asembly registration tool). The Assembly Registration tool reads the metadata within an assembly and adds the necessary entries to the registry, which allows COM clients to create .NET Framework classes transparently. This utility is necessary when you need to expose to COM e .exe (winform application) .net assembly. You can create a type libray in this way. MyAssembly.dll can be also MyAssembly.exe

It is important that you do not check the
Project/Properties/Application/Assembly Information... Make assembly COM-Visible.
This option will set [assembly: ConVisible(true)] in the AssemblyInfo.cs file
Which will make all the Class in the Project COM visible. This in practice will make C# to generate new Guids for each class on which we did not specify a Guid attribute each time we recompile, causing a registry bloat.
It is much better to set
[assembly: ConVisible(false)], and use ComVisible(true) at class level to specify which class should be visible for COM interop .