In the past I have used OASIS a freeware help authoring tool. Its a what you see is what you get style program.
It is quite old now and has not changed very much recently. Also it does not work with the new compiled HTML. However if you want to do the traditional help files it could be useful. It takes a bit of setting up but if you want to do the traditional help files it could be useful.
The URL is:

http://fire.adept.co.za/~oasisdev/

Let me know if this helps