If you have any need to build .hlp files, check out helpMATIC Pro. The shareware version is fully functional (except that it puts a small notice at the bottom of every screen indicating that the tool is a shareware version), so you can try it out risk free. I was able to get this help together within a few evenings of using the tool. It's the only one I've ever used, so I can't compare it; however, it gave me no reason to need to try anything else. Very intuitive and very reasonably priced.