You are best off getting the music into your PC from the CD, either rip it as mp3 or wav. Put on the soundtrack track

For spoken input the audio in on most soundcards isn't sensitive enough for a decent mic, and you will need in addition to the mic, a microphone preamp, or small audio mixer. However, that all might seem overkill for a bit of voiceover.

So can I suggest you look at one of the new USB semi-pro mics (Something like this: Samson Q1U at DV247.COM ) which you can plug directly into a spare USB slot and away you go.

Record your voiceover to a separate audio track and then you can set the levels independently between VO and music. I also think you can keyframe animate audio levels in elements so you can duck the music when you are speaking and bring it back up again when you aren't.

Hope this helps