Green hard disks I wouldn't touch with a 10ft barge pole. They are just about guaranteed to fail after a year or two.
After spending a year slowly investigating, I ended up using my old MacBook Pro from 2006 that has a dead battery as a NAS with a couple of external eSATA cases. I stuck it in an upside-down "V" position behind the TV so that it doesn't automatically sleep which it will do with the lid closed. No having to worry about what software to use or other issues as I just used the drives I had that already have all my stuff on them. I think down the track I'll get a couple of 3TB drives and make a RAID 1 mirror from them for safety though.
Safety? RAID isn't a substitute for backing data up. Think house burning down, thieves, viruses, corruptions (hardware or software). It only offers protection against disk failure.
I've never had a WD green fail yet, and I wouldn't care if they did really either. As I said everything that's important to me I keep offsite at work.