My 450gb iTunes library resides on an external hard drive which I fear is failing. The mac is an older iMac with USB 2.0, FW800.i connect via FireWire 800. I use the iMac for reading and burning discs, and as a hub to stream airplay around the house. Questions: 1. Would a USB drive be adequate for iTunes to read off and stream audio and video? It will only be capable of 2.0 speeds. 2. Whatever drive I choose; should it be powered? 3. If I stay with FW800, any recommendations? This iMac predates thunderbolt. Thanks!