Problem with encoding in export to Excel from C# WebPart -

i have simple c# webpart (written wss 3.0). ones of functionality exporting data excel. working have problem displaying polish letters. try change everything, read lot of forums , blogs , still don't know i'm doing wrong. hear code:

httpcontext.current.response.clear();             httpcontext.current.response.addheader("content-disposition", string.format("attachment; filename={0}.xls", filename));             httpcontext.current.response.contenttype = "application/ms-excel"; httpcontext.current.response.contentencoding =      system.text.encoding.getencoding(1250); // correct encoding code  using (stringwriter sw = new stringwriter()) {                     using (htmltextwriter htw = new htmltextwriter(sw))     {                          table table = new table();         tablerow row = new tablerow();          // (...) fills header row          table.rows.add(row);          foreach (user user in userlists)         {             tablerow row1 = new tablerow();              // (...)  fills row data              table.rows.add(row1);         }          table.rendercontrol(htw);          httpcontext.current.response.write(sw.tostring());         httpcontext.current.response.end();     } } 

i used similar method exporting data csv file , there no problem displaying polish signs. have know i'm doing wrong??

sometimes when have issues when importing data, helps reset data formats parts screwed up. might want try resetting language doc make sure issue isn't code excel defaulting english obscure reason. luck.