Pdf To Djvu Gui is a freeware win32 application that converts any pdf into Djvu.
Djvu files are generally smaller than the pdf files and are good looking.
Pdf To Djvu Gui comes with a nice installer since Cygwin is needed. Launch the installer and follow the instructions, the installer is pretty self-explanatory.
Pdf To Djvu Gui is based on pdf2djvu which is a Linux project.
I ported this project over windows since there was no free option generating djvu files over windows, at least known to me.