I've never really fully understood the concept. Do you just use one so that you centralize your media and so you're able to access your files without having to have your main computer on all the time? I use an Apple TV. I wirelessly stream my media from my main computer - which has some external drives plugged into it that have all my media on them. This media is then linked into iTunes. I'm just wondering what if anything an iTunes server could/would do for me... (i guess if you have to ask your probably don't need one, but I'm just curious). Also this is a bit off topic, but is there a way in iTunes to have iTunes continually check your media folders for updated files?