Are you mainly needing the software to do the drawing/art part?

here's some choices to explore from cnet- Illustration Software
http://download.cnet.com/windows/ill...?tag=ltcol;nav

Desktop Publishing Software -
http://download.cnet.com/windows/des...?tag=ltcol;nav

If you are sending off to a printer for the finished book, you might even be able to use hand drawn images.
Or hand draw/sketch and use a scanner to import on to computer.