Easy Solution: Have you looked for the sound track of the movie? It may be on there.
Do it Youself solution: Do you have a microphone on your PC? If so, I recommend downloading this program called CdEx
http://sourceforge.net/projects/cdexos
You can use it to rip cds and save them as mp3s, and record audio and save it in various formats, such as wav and mp3.
Just download and install the program. Run it, then go to Tools, and choose the option "Record from Analog Input". From there, choose where to save the recording, it's name and the format (for mp3, choose Lame MP3 Encoder), hit record to start, and stop to save it. Your done!