Some good news on the Windows Vista / WinHelp front. Microsoft have now decided that Longhorn users can download the WinHelp32 engine. Originally MS indicated WinHelp would not work on Windows Vista at all.
Its official. The notice has been published as a KB article KB917607 at http://support.microsoft.com/kb/917607/en-us
„… Users who want to view .hlp files must download the program from the Microsoft Download Center, and then install it on their computers. The download for Windows Help is still in development and will not be available for the release of Windows Vista Beta 2…“