FYI - I installed Double Twist on my PC to see if it would sync with my Eris. It worked great. Once I mounted my Eris, it showed up as a device and I could drag music to it no problem. It also ready my iTunes library no problem. The only gotcha is that if you enable syncing music - it by default wants to sync everything. I disabled that because like with all my mp3 players, I like to manually control syncing. The Amazon Music store isn't integrated into the Windows version, but I gather it's coming in the near future. I tried syncing with Media Monkey, but couldn't get it to see my Eris. I may try again. Double Twist is pretty bare bones, but it got the job done.