Paul,
Just to add that you may be able to avoid having to install Visual Studio .NET in order to create and view Help 2.0 files. There is a hack you can use to install the VSHIK without first installing Visual Studio .NET, which is otherwise a prerequisite for running the VSHIK setup program. In addition, the Help 2.0 viewer components are now shipped with a number of applications other than Visual Studio .NET, including Office 2007 and the .NET Framework SDK. The latter is a free download from the Microsoft site, and a fraction of the size of a full Visual Studio .NET installation.
See this page for details:
http://helpware.net/mshelp2/h20.htm
I guess you know that Help 2.0 is best avoided unless you want to integrate your content into an existing Help 2.0 collection, such as Microsoft's Visual Studio .NET help or MSDN library, or Borland's C# Builder documentation. Files in Help 2.0 format aren't designed to be viewed as standalone files.
Pete