I just got MSP8 audio working correctly on Win7 this morning. http://forum.corel.com/EN/viewtopic.php?f=52&t=47408
Note the post following the link, where I correct the error and explain that the entire vio folder was changed. I just posted it, and it is pending review as I write this.
I have tried a lot of programs since MSP was discontinued, and have not been happy with any of them. Granted, MSP8 lacks some mp4 support, but I imagine codecs might be available to fix that.