How do I protect Excel Workbook but allow to add new sheets‏   

Hi,
I am exporting some application data to Excel workbook through my C# code.
I would like to Lock the Workbook to prevent users to edit the name of the 
sheet and some column data.
But I need to allow user to add new sheet.
Workbook.Protect method allows me to Lock the Structure of the workbook 
which includes not allowing to add new sheet.
But As I said I need allow user nothing but adding newworksheet.
How Do I do that ?

Thanks,
-Som

date: Fri, 20 Jun 2008 10:40:01 -0700   author:   Som_Dev