you cant play mp3 files directly, you will need a codec for this, like an mp3 player OCX or the same...

anyway.. if u want to use flash for the game, just make your game in Macromedia Flash 5 (or 6), that will can play mp3 files and a whole things you needed.. then complie that in an executable (i think you can do it with the FPlay32.exe or the same named thingie)

Jim.