Please bear with my many questions, but I'm so confused. I have an iMac running 10.5.8 and an Air on Snow Leopard. Should I upgrade everything to Lion now, in order to use iCloud? Do I HAVE to use iCloud yet? Also, my son buys music with my Apple ID/itunes account. My mobile me is a "family plan," but I'm the only one who uses the iDisk (for data storage). The others just use the me.com email address. Also, my son's got an iphone 4s coming, which means iCloud is coming to our house in a couple days. I don't want his music. I don't want any of my stuff cohabitating with anyone else's. So is iCloud linked to the email or Apple ID or what? Help.