If you can use a pc newer than 20 years, running f.ex. WinXP, I will recommend the very nice "S5 for Windows" from IBH-Softec http://www.ibhsoftec-sps.de/english/Selection_S5_S7.htm. It has built-in emulator to run the Simatic COM-packages (NCM, CP1430, CP525, COM TEXT etc.). You will have to buy it to get online.