I am using Word 2007 for a document which is about 100 pages, with about 20 chapter titles which appear as headers on the even pages. The title of the document appears as a header on odd numbered pages beginning with page 3. I have made a contents page which is page 2. Page 1 is a title page (not a MS Cover Page) and has no header since I have checked “Different First Page” in the page layout. My problem is that the title of the first chapter “Preface” appears as a header on page 2, the contents page. How can I eliminate this header?

What you want is a different header for each section.
To do this:
1) Create a section break at the end of the content page
2) Go to the header of the second section (page 3). Click on the 'Link to Previous' button in the Navigation section of Header & Footer tab. The 'Same as Previous' indicator on the right of the header should disappear.

Now the headers are not linked and you can have a different header in each section.

Cheers,
Andrew