I recently tried to convert CHM (Windows Help File) to PDF. There're many methods to achieve this. Now I give you an easiest way to make your PDF file from CHM using chm2pdf script.
You can download this script from the main
web site. Just follow the manual guide to install and make it work. If you're using Ubuntu, I have a simpler way to do it.
First, open your Ubuntu Software Center and type "chm2pdf" then install it.
After finishing the installation, let's convert your first pdf file from chm!
Have fun!