Here is the enclosure:
http://www.pc-pitstop.com/sas_cables_enclosures/sas4x41u.aspI outfitted this with four (4) 2tb WD Cavier Green Sata Drives on sale for $175 ea.
I then got a RAID Controller Card for you PC. The exact model will depend on your card slots, and there are various types listed that match the enclosure on the above page. Configuring it was not a big deal. Snap the card in, power up and as it is loading in DOS, there is a menu which pops up which says, something like "Press F8 to configure." Then the RAID Software runs and you tell it how many drives are in the unit (they all should be listed), then tell the Card whether to RAID 0, 1 or 5 the drives. Since this was a back up, I did RAID 0. Then, all the SATA units will show up as as one drive which you can name.
I named mine T Backup.
I have yet another back up which is USB based, but I only do it about once every two months. The 4 Satas back up every few days.
PM Me if you want additional info.