Hello, I was experiencing the same problem. I'm sitting here at work so I couldn't start tearing the phone apart so I tried Max's suggestion about the cleaning the earphone jack. It worked! after blowing the earphone jack out with air the noise is completely gone. easy fix this time.
...Sharepod http://www.getsharepod.com/ One of the best programs I've found for PC... or Senuti for mac your music should be in \music\itunes\ either itunes media or just music. Like Mayer said your music wouldn't be on your iPod without being on your computer.