I'll go against everyone else and recomend a NAS enclosure. I have this: http://www.newegg.com/Product/Product.aspx?Item=N82E16822155009 and love it. After getting off of the firmware that shipped with it (shouldn't be an issue now) I had no stability issues at all.
All you would need to do is pick out hard drives ("Green" drives work great in here) and go. If you won't have that much saved/backed up to it, you can set the drives in RAID1 so it's all mirrored just in case one happens to die on you.
I have that nas and I love it but for business I can't use it because it has a HUGEEE flaw. When you want to share a folder with two users, the NAS will make two different share folders. For example say I want to share folder in the nas called "data" with two users. The nas would create a share folder data for user1 and data-1 for user2. When you browse the network from a windows box, you would see two shares called data and data-1. What was d-link thinking??
Maybe I missed something in the manual but I can't find a way around it. Do you have that same problem???