Winhelp32.exe wasn't included in Vista. It takes up about 255k of disk space.
The Winhelp32.exe program that comes with Vista takes up 9k that tells you the old help isn't supported because its old.
Help from your existing programs probably won't work!
That means you have to add it from the windows website after verifying your Original Windows Software or copy it over from XP and futz with it to make it work. This seems like a time wasting enhancement to me.
Why didn't they just call their new help software something else?
Is it possible that they couldn't figure out a way to enhance the old help, so they trashed it? hmmm.
I don't like buying a new everything every time I upgrade.
Thats like finding a new wife because you moved.
Its expensive, it takes time to relearn, and the old one worked just find, so why replace.
I think this may be one of Microsofts failings.
I've written oodles of applications with VB 6 and ASP classic.
It would take months to rewrite them for the sake of upgrading to VB.Net or ASP.Net. 
I just hope Vista doesn't go the way of the Windows Millenium Edition.