WinHelp32 Download for Vista (32bit and 64bit versions) is now available on the Microsoft Download Center.
With this release, Vista customers can now install the WinHelp application on their system and securely view .HLP files on Windows Vista. This release applies to Windows Vista x86 and x64 only.
The WinHelp for Vista KB article will be updated with release documentation soon. http://support.microsoft.com/kb/917607/en-us