[kagenaki koe]

the only reason you won't be able to play your friends' mp3s is if it has DRM (re: it's licensed to one account or copy protected). itunes does slow down (not the drive but the app itself) if you have a fairly large collection (in my case 17,000 songs). it isn't the app that takes up a lot of space, it's your own actual record collection and how it has been encoded ex. a song encoded as 320 kbps mp3 is about a 15 mb file (lossless is about 20 to 30 mb), but encoded as 192 or lower the file size is about half that. so if someone had a record collection encoded at 192 or lower, he won't use as much hard drive space as someone whose collection is 320 kbps (or lossless)