Dude, I would highly recommend the Retr0brite. Its awesome!! All my Classic Macs are white now! Get Clairol Pro 40 cream developer and a brush. Clean the case well with Simple Green and brush the developer on the case and leave it in the sun. Every 30 min or so reapply the creme with the brush. in about 4-6 hours your Mac will look brand new.

http://retr0bright.wikispaces.com/