Found another solution without downloading HPC:
oXL = new Excel.Application();
oXL.Visible = true;
oWB = (Excel._Workbook)(oXL.Workbooks.Open(@"c:\Excelbook with macro.xlsm", Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value));
oWB.RunAutoMacros(XlRunAutoMacro.xlAutoOpen);