There are several ways to do and enforce it:
1) You can customize the code template that VS.NET uses for new classes. See
my MSDN KB article:
HOWTO: Changing the source code of templates used by Visual Studio .NET
wizards.
http://support.microsoft.com/default.aspx?scid=kb;en-us;555160
2) You can create an add-in to do it automatically each time a new class is
created. This requires some programming effort and time.
3) With my add-in (below) you can easily:
- Insert a custom template with a single mouse clic or keyboard shortcut.
- Create an external operation to add masively headers to each existing
class. See the External Operations (Extensibility) feature
- Review that each class has the proper header. See the Review Mandatory
Text feature.

Signature
Carlos J. Quintero
MZ-Tools 4.0: Productivity add-ins for Visual Studio .NET
You can code, design and document much faster.
http://www.mztools.com
> As per a suggestion (http://blogs.msdn.com/brada/articles/361363.aspx) I
> read, putting copyright notices sounds like a great idea. However,
[quoted text clipped - 3 lines]
>
> Thanks.