Open XML is a wondefull technology to manipulate and create Office files, yesterday the VSTO team released the Open XML Package Editor Power Tool for VS 2010.. Thanks!
From the VSTO Team blog:
We are happy to announce that today we are releasing the Open XML Package Editor Power Tool for Visual Studio 2010 on Visual Studio Gallery. This Power Tool is a Visual Studio add-in that provides an easy way to parse and edit Open Packaging Conventions files, including Word, Excel and PowerPoint documents. This Power Tool enables you to do the following tasks: