I have an older, round base, lamp style iMac. It has a lot of music on it. I just tried to add it to the home share, and I realized the MacID on it is in the old mac.com format. I want to switch it to the new iCloud.com format, but I'm not sure how. It seems the only option is to deauthorize the iTunes, and then reauthorize it with the new MacID. Will that work, or will I lose all the purchased items, purchased via the old MacID through iTunes? I'd hate to lose those tunes. I'd also hate to lose access to the hundreds of CD's I ripped, via iTunes. Help?!?