I have a lot of music. My NW-HD1 died, which was too bad, but it's not the end of the world. I don't know what to do because it didn't have enough space to carry my entire music collection with me. When I first started with the idea of HDD units it was to carry everything with you with no extra discs. What a great idea. But for those of us who have a lot of music by buying albums over many years it becomes very important to have high capacity. Thus my vote for 30-40. More would be better, but cost to capacity this would be the best. This will soon be a very serious problem for Sony unless it is resolved. High capacity is important.