i'm pretty sure .ms files have NO relation to .dvr-ms files, since the latter is just Windows Media Center Edition's wrapper for video files it creates, that uses simple MPEG-2 compression (like PSS files). feel free to test that though, since i am not 100% sure.
ToWav Music Convertor should do the job (
CTPAX-X - Файловый архив , or google it). it supposedly covers a wide variety of filetypes, and it lists your game (with .ms extension, no less). if you google the page, you can translate it from it's original Ukranian, if you like.
one more thing i found to be of interest:
File extension details - files How To (by File Extension Seeker) a quite comprehensive list of Playstation 1 thru 3 extensions that are known to be capable of being ripped.
i hope this was abit helpful
-df