I have an iMac 27" i7 2010 and I am currently running iTunes from 3x1.5 tb external USB drives. iTunes can be a bit laggy atntimes loading artwork etc and I also find that streaming to my ATV 2 can take a bit of time to buffer. I have a 40 mega Internet connection so this shouldn't be the problem. I am thinking of upgrading to 2x3 tb drives and I'm not sure if going for the FireWire 800 option is going to make a big difference. I can't seem to find any real information on actual speeds on YouTube etc. Thanks for your help in advance.