hard drive setup?

I was hoping someone coulld give me some advice on configuring my hard drives. Currently I have 3 drives, 120gb partition into 40gb and a 70gb partitions. The operating system is on the 40gb partition. The other two drives are in a raid 0 array, matching 80gb drives. As of now I'm total full on storage, so I purchased 2x 250gb sata drives.

My question is how should I setup these drives. A large portion of my storage is dvds on my computer which are served to other xboxs consoles located in the house. I would really like to combine the new 250 drives so they are one but I'm worried about failure in the long run. These two drives are for the most part just for servering video content.

Any advice would be great

Thanks