Jim,
I'd be tempted to just use whatever the default .htm client is for the machine using ShellExecute(). Originally you said you don't want a separate browser window popping up. Check
www.activex.com and see if anything is there. If you are using HTML help I think you can be sure that the WebBrowse control would be installed on the machine.
>This will be included in a commercial package and I can't depend on IE being installed at the client site. I believe the control relies on IE4 or greater doesn't it? Do you know of any controls (3rd party would be OK) that are completely free standing, unrelated to the browser on the client's system?