As of this week, Microsoft Office SharePoint Designer is now available for free. You can download it from http://office.microsoft.com/en-us/sharepointdesigner/default.aspx. This will be a great tool for use in editing the pages in the Default Site in Commerce Server 2009 – or any other supporting file (e.g. – Resource File) or page created in SharePoint Commerce Services on top of Commerce Server 2009. Hope this help!