Microsoft is allowing Vista users to download a component that will allow them to use their old .hlp help files. They had removed it from Vista since it had been stagnant with no new updates, and was not something they planned to use. The only issue is that other applications used the same files and would no longer have access to them in the standard Vista install.
I think Microsoft has taken the right action on this. There is no need for them to support a thousand different file formats that are basically obsolete. However, since some users still have applications that use it, it should be fairly easy for them to offer it as an option for those that need it. It may seem silly to support such an old standard, but if you want users to migrate to Vista and you don’t support something they need, then you are just delaying their acceptance of it. Just how far you should go with backwards compatibility is something that you basically can’t win at. Include too many and you are accused of bloatware, include too few and you are seen as not supporting your customers. You can get it at BetaNews fileforum here.