C＃ - 使用国际设置的Excel数字格式问题

I am trying to write to an Excel 2003 spreadsheet using c# 3.5. However I am unable to get this to function correctly across different country settings. The country settings are either English or German. These two settings have different decimal and thousands settings. Everything works fine unless a user has changed the decimal and thousands separators in the International settings of the Options screen. Can anybody help as I feel I can no longer see the wood for the trees and am missing something obvious.I am trying to write to an Excel 2003 spreadshe