I need a 4-bay NAS just for home and family use, storing pictures and documents and whatnot. We have too many PCs to use external drives without hassle. Streaming to the PS3 with PS3MediaServer would be nice although not required. I want to start with 1 WD Red and expand into RAID 5 as I need later. I was looking at the Synology DS413, DS414, and DS412+. Is the primary difference between these just RAM and CPU power?