Based on this very useful Ken Rockwell article I read a long time ago and reskimmed today since I just bought an iPod touch, I changed my CD rip (Import) iTunes settings from MP3 at 160kbps to AAC at 128kbps with Variable Bitrate Encoding (VBR, sic) enabled. I hope I don’t have any trouble (skips or who knows what else) running these on my 40GB iPod (monochrome) or my 4GB iPod mini.