如何在Excel工作簿中存储信息

I'm programing an Excel Addin with VS2008 and VSTO(C#) over Office 2007. This addin needs to store information embedded or inside the Workbook to recover some status when the user opens again the Workbook with this kind of information. Before save the Workbook, the Addin serialize in XML all the information, and after open a WorkBook the Addin try to deserialize this information if it found it.I'm programing an Excel Addin with VS2008 and V