may I ask what kind of software to use for writing help files? Something recommendable?

TIA and friendly greetings,

Ralph

We haven't tried any of those products.  HelpStudio Lite (the free version) came packaged with the Visual Studio SDK and we liked it much more than RoboHelp, so we started using it.  We went to the full version of HelpStudio because the full version is required to compile .chm files.  The lite version only does Help 2.0 which requires the Microsoft Document Viewer (think Visual Studio help).

A word of caution, though, we tried the DocumentX for our class libraries initially, and it had lots of issues with compiling help from our DLLs.  It took some 19 hours to analyze and build the help for just the 4 core SF DLLs, and half of the time would crash.  The SandCastle script runs in about 10 minutes.