Last week WD stared selling the WD 4TB WD4000FYYZ -- 1.2mm hour MTBF -- 5 year warranty -- 64MB cache -- 800GB platters -- 7200 rpm -- $436 This week WD started selling the WD My Book 4TB USB 3.0 External Hard Drive. About $200. Probably 5400rpm. Anyone know what's inside that thing? I gather I'd void my warranty if I bought one and opened it up. What I really want is the bare drive WD 4TB WD40EFRX - Red, 5400 rpm. Maybe next week? Hope it has 4 platters.