I think your plan largely relies on what you are trying to achieve. Are you looking at setting up a RAID array, duplication or just massive storage? Are you keeping your ripped DVDs/Blu Rays at the original compression and file sizes or are you going to shrink the main movie and remove the menus and extras?
I did the latter, I stripped out all the extra stuff and ripped just the main movies of my DVDs and shrunk most of them to about 1.5GB (CGI/action flicks with a lot of special affects I either kept original size or shrunk to about 4GB). With this, I am able to save my DVD's to a 1.5TB Caviar Green drive, duplicate it to another Caviar Green 1.5TB drive and I don't have to worry about losing my hard work. Currently, I have about 500 DVD's set up like this - converted to AVI (Xvid) on my server that I stream to my HTPC in my family room.