Most of the songs I get (about 80%) are from CDs, and I've always used apple lossless. So, my files are like this: 48% Apple Lossless, 2% AAC, 7% AIFF, 43% MP3. I have about 1500 Songs, all of which add up to 20 GB. OK, so, after the Nano commerical, i assume 4GB = 1000 songs, but in my case, it seem to equal 300 songs. So, my real question is what is the best file type for freeing up HD space, iPod space, but still keeping reasonable quality?? Thanks so much in advance.