Add a Chart to a Worksheet Programmatically (C#)
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dv_wrcore/html/wrtskcodeaddingcharttoworksheetprogrammaticallyc.asp
Creating a Chart in Excel Based on SQL Server Data
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/odc_vsto2003_ta/html/odc_vstexlchrt.asp