I just ordered my Mac Pro and am eagerly awaiting shipping and arrival. In the meantime, I`d like to get the remaining 3 hdd`s ordered and on their way to me and am looking for some sound advice. With so much debate and back and forth with WD`s Caviar Green vs Caviar Black: 5400-7200rpm variable speed vs 7200rpm / performance use vs storage use / whether the variable speed will lessen the lifespan of the Green drive / etc, etc, etc... I am wondering if I can get some sound, sage advice based on my needs for these drives so I can move forward and not be so concerned or down right terrified that they aren`t going to live up to my needs. Simply put... Bay/Drive 1 will be a 2tb that Apple includes (stock drive), which seems to be the WD Caviar Black - perhaps. I will keep my personal/business photos/videos/documents and massive itunes library on it. Bay/Drive 2 will be personal photo/video/document and itunes library backup. Bay/Drive 3 will be business photo/video/document and contracts backup. Bay/Drive 4 will either be a backup for Bay/Drive 1. No RAID or other setup. Just plug in and go as is. Since my drives 2-3 are being used for storage purposes and backups...it seems on paper that the WD Green 2tb will be fine with variable 5400-7200tb because the large majority of MY performance is coming from Bay/Drive 1. The rest are merely places where I will keep copies of everything else. I see the WD Caviar Green 2tb for $110 on Amazon (OEM). I see the WD Caviar Black 2tb for $150 - $180 (retail version) and higher. Am I going to see any difference in these drives, in real world terms for MY usage? Just dragging and dropping files from one drive to the next. Or running Time Machine to make a copy. If I truly had a drive fail me, I`m not concerned about the read/write speed of the back-up drive, as I would just replace the faulty drive with the same type it was. Thanks.