Hi, I know a free chm editor if you use vs 2005 standard edition or greater comes with the visual studio sdk (might have been in the power toys included in this package).  Here is a link to sdk v3: http://www.microsoft.com/downloads/details.aspx?FamilyID=7e0fdd66-698a-4e6a-b373-bd0642847ab7&DisplayLang=en
Note: I rember the chm tool seemed like it was a fairly complete tool, but incrediably slow during startup of the program.
-ian