Isnt it obvious? Itunes does not allow multiple computer syncing. Once synced to one computer, the sync to the next will delete your previous sync, a.k.a all songs from previous sync from previous computer will be gone.

These users are mainly those who wants to "share" songs to their liking, which is treading on the realm of piracy. They are used to the cheap MP3 players that works like thumbdrives where you can drag-n-drop them like files and oblivious about other things like album metadatas and artworks. That's where the hate is flowing from, since Apple stops them in their tracks.

I like my songs with nice album art, tagged proper, and i absolutely LOVE the FREE contents on iTunes. Yes, there are free contents on iTunes, all you need to do is Google up how to create an account, and it's FREE to do so. Lazy buggers need not apply, go with your Yamipods and Senutis.