I have Midisoft Studio, Version 4.0, that is a very good program, but it does not work with Windows XP. And all my files were saved in SNG format, a format that other programs don't open. I don't know what I can do to play my files.
It seems that the latest version of the application is compatible with Windows XP and can work with SNG files that were created in a previous version. However, it seems that the official website of the developer is down and there is no way to download the program anymore. In this matter, I suggest that you use Google to find a website like Amazon or Ebay, from where you can purchase the application online.