Complete instructions on ripping music files can be found at the Windows Media Player 11 How-to Center [for 7, Vista], [for XP]. But you can use ripped audio files from any music player you prefer. Remember that Matrix Mic can only play Wav file format.
Check you local library for sound effects CDs or enter Google search phrase "sound effects" to find audio files available for download (many are free and have public domain usage and copyrights). The well equipped sound person should have at least one Wav editing utility program. Here are a couple that are free and simple to use. There are others if you dig around the Web a bit.