I doubt you will have 4TB when all done. The xbox is extremely picky about what it will play, especially in media center.
I been trying to do the same and all i can get media center to play is .wmv.
Currently I stream .dvix to the xbox through the videos folder. Not quite what I was looking for.
This is what I got setup on my moms PC, and what I wanted for the xbox, but I cant get it to work.http://www3.mediafire.com/imgbnc.php/9075e2ab33a7c1a29b9ead020321105d6g.jpg
Im buying a projector for xmas, so I guess I will use a PC to watch my DvD collection like this on my new 11 foot screen. And use the xbox 360 just for games.