No preface numbering

Hello

I'd like to stop preface numbrering, and having the first chapter 
numbrered from the very start.
IE, I have a 6 page preface, I do not want it numbered, but I want the 
first chapter numbered 7.

Is it possible?

Thanks

Christian Brugeron
Expert PDF/PostScript - Automatisation de l'嶮ition - XML/XSLT/XSL-FO