I have legal versions of Microsoft on both computers. I've tried burning MP3 and WMP formats, both without any success. I've tried using Nero 6 (burning MP3s) on a test burn first without any problems. I can burn the CD fine and it will play perfectly in the computer. However, when I try to play it in the car or on my portable CD player, it only works for about 5 songs. I had the same problem when trying to burn with Windows Media Player and another program I have here, "Record It". I have used various quality of CDs all with failures. The whole thing doesn't worry me now because the MP3 CD Maker software is perfect, every time.