Therefore, starting with the Microsoft Windows Vista and the Microsoft Windows Server Code Name "Longhorn" operating system releases, the Windows Help program will not ship as a component of Windows. Also, third-party programs that include .hlp files are prohibited from redistributing the Windows Help program together with their products. Users who want to view 32-bit .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 be available in early 2007.
InfoQ Homepage News Updated: In Case You Missed It: Vista Does Not Support .HLP Files