var
Form1: TForm1;
fname: string='C:\Рабочая\1файл.xls';
Exel,Book,Sheet:OleVariant;

implementation

procedure TForm1.Button1Click(Sender: TObject);
begin
try
Screen.Cursor:=crHourGlass;
 try
  Exel:=GetActiveOleObject('Excel.Application');
 except
  Exel:=CreateOleObject('Excel.Application');
 end;

try
 Exel.WorkBooks('1файл.xls').Activate
except
 Exel.WorkBooks.Open(fname,false);
end;

Sheet:=Exel.ActiveWorkBook.Sheets[1];  
Sheet.Range('A1:B3').Select;

finally
 Screen.Cursor:=crDefault;
end;

end;