You are correct. My 35 gig collection took 60 gigs. I was expecting it to take 40, but it's at 35. I know this because I only had a couple meg free when I had ripped all my CDs on my empty 60 gig. Then I converted all to ogg. All in all, 60%*wavsize=ogg size, for my music which is all forms of rock. It seems that disortion-plentiful music is ~60% and distortion-free runs ~40%.