I've looked at FreeNAS and it looks nice, but I'm leaning toward UnRAID. Has the ability for dual drive parity, but if more than two drives die you only lose the data on the drives that are over the parity count (3 drive failures with dual parity, you lose one drive worth of data instead of everything). It isn't built for speed, but it does have plugins for xbmc, plex, couchpotato, headphones, sickbeard, sanzb, bittorrent, etc. Nice software, but it isn't free like FreeNAS.