COM object vs interface

Hi,
I am trying to expose my classes from VB.NET to VBA. I am currently writing my own interface for each class e.g.:

Imports System.Runtime.InteropServices
<Guid("4c42de70-4bdf-11dc-8314-0800200c9a66"), _
InterfaceType(ComInterfaceType.InterfaceIsIDispatch)> _
Public Interface _Optimizer
...
End Interface

and afterward link the interface with my classes and so they are exposed to VBA.
There is another possiblilty I just realized in .NET and that is to select a COM class in the wizard (Add>new item>COM class)

Since I am new to interface programming, what is the difference? It seems that I do not have to write any interface at all with the second method.
It would be great if someone can elaborate this.
Thanks :)

What kind of .NET project (VS 2003?) do you start with to create a COM Object creatable using CreateObject?

Thanks!

Dave

Hi Dave,
I use VS2005. I am not sure what you mean by createobject. I click with the right mouse button on my vb project and than (Add>new item>COM class)

Visual Studio automatically creates all of the necassary interfaces when you create a COM class.

Does it have to be a special type of project? Does this work with 2003?

The ComClass is new in 2005.