Soundproofing a Cubicle?

Anon! A Mouse Cowered! asks: "I work in a 10 x 10 ft. cubicle that's about as low-end as it can be (my back wall is made of my filing cabinets). I have a cheap set of speakers on my desktop for internet radio, but if I play anything other than light jazz or classical at anything above a squeak, it's annoying to my coworkers. Are there any other Dilberts (or Wallys, even), who can offer ideas on making a workspace more livable so that I can enjoy my Primus albums at an audible volume while working?"