Windows help (WinHlp32.exe) is a program that was available in all versions of Windows, but was not there in Vista. It enables to view help files stored on older .hlp file format. As this program did not meets the Microsoft Standards, so it was not present in Vista.
But now Microsoft has updated this program which supports Vista. This can be downloaded from
Windows Help program (WinHlp32.exe) for Windows Vista
So if you want to view 32-bit .hlp files in Vista, you must download and install this program.