Error while trying to put together a document with xsltproc

Hi :) .  I'm a docbook n00b.  Just getting my feet wet here.  I configured my mac mini to compile docbook xml files.  I got the information on how to configure it from this site:

http://www.working-software.com/node/18

I was looking at the below tutorial.

http://opensource.bureau-cornavin.com/crash-course/en/declaration.html#shared-text

I'm a little confused why it's not working.  The error message isn't really telling me anything specific (again, new to this stuff :) ).

Command line:

% xsltproc --output my_content.fo $XSL/fo/docbook.xsl my_content.xml

my_content.xml:2: parser error : SystemLiteral " or ' expected
<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.4//EN" [
                                                           ^
my_content.xml:2: parser error : SYSTEM or PUBLIC, the URI is missing

<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.4//EN" [
                                                           ^
my_content.xml:9: parser error : Entity 'cereals' not defined
      Marketing study about &cereals;

                                     ^
my_content.xml:17: parser error : Entity 'cereals' not defined
      This study describes the expected impact of the new &cereals; product,
                                                                   ^

my_content.xml:19: parser error : Entity 'orange-juice' not defined
      the &orange-juice;.
                        ^
unable to parse my_content.xml

Here's the file:

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.4//EN" [
  <!ENTITY cereals "<productname>Frobozz Cerals</productname>">

  <!ENTITY orange-juice "<productname>Hourmade Orange Juice</productname>">
]>
<book id="marketing-study" lang="en">
  <bookinfo>
     <title>

        Marketing study about &cereals;
     </title>
  </bookinfo>
  <chapter id="introduction">
     <title>
        Introduction
     </title>
     <para> 

        This study describes the expected impact of the new &cereals; product,
        and examines the opportunity of an advertising campain combined with
        the &orange-juice;.
     </para>

 </chapter>
</book>

If this is the wrong forum, sorry.  If there is a better place suited to answer this question (especially for those that are new to this), please point me in the right direction.