I have a Zune, an IPOD NANO, and a palm pc that plays music. The IPOD nano has appropriate technology for working out. The zune is not intended to bounce around and can be severely damaged if you do so. They have different memory chips in them. Having said that - I find the zune much easier to use and work with and has much better sound. I hate the "wheel" on ipods. BUT, for working out I always use my nano. Additionally, the zune really is too bulky to work out with - it would be like wearing 10 nanos. The zune will keep my kids quiet for hours. I have 450 cd's and they are all on my zune - and only fill up about 1/2 of the capacity. I obviously can't fit nearly that much on my 8gb nano.