So ideally, you want a single device on the network to handle the drives and media serving?
Drobo would be what first comes to mind.
The other option is build a cheap PC (or take your existing one), and either:
- plug in one (or 2)of
these external raid enclosures with a couple of
these 3 TB drives in each, you can set those drives as RAID1 (or a couple more like RAID0 or JBOD that you wouldnt really want to use) with toggle switches, so it is VERY easy.
- toss a bunch of hard drives directly inside it. Most motherboards can support 4+ drives, but the problem would be having enough room to mount them internally, so make sure the case you get has room or you find some brackets to use 5.25 drive bays with your 3.5" drives. The RAID software in windows 7 is pretty good and would save you finding a hardware raid controller, and is pretty straightforward once you find your way into Disk Management.
RAID 1 (or RAID5) both essentially give you a small measure of redundancy to ease your pain in recovery in terms of a disc failure. It is not a backup solution, but it essentially mirrors drive content without using the full space (ie 2x 1 Tb drives give you about 1.33 TB of drive space when set up in RAID 1 )