Comment "I won't need 16,000 RPM drives" (Score 1) 609
More than that, you might not need even 7200 RPM drives. There are large capacity "green line" drives from some manufacturers, 5400 RPM, that might be perfectly enough.
I'm sure other posters will have much better recommendations as to how the overall setup should look like, but for whatever it's worth from me - stay away from consumer NAS solutions, they have usually quite small transfers (and I guess its important to you, with files being rather big). Large tower with plenty of space inside + Atom motherboard should be enough, otoh (as long as that Atom board has enough SATA ports...)