Budget build with parts on hand

[psilikon]

I want to put together what I would describe as a budget build with some parts I happen to have laying around the shop. Here is a list of what I currently have:

1. SuperMicro X7SBA
2. Intel Core2 Quad Q9400
3. 8GB KVR667D2D8P5/2G (ECC)

I would need to order a quality PSU as well as some HDs. I was thinking about 2 red WD10EFRX drives (1TB each).

The NAS will be used in a small office with about 5 users maximum.

What file system should I use with only two drives. Can I get by with using the onboard controller in a RAID 1 config (what I intend to do) and then use a UFS setup? Any caveats when placing a Quickbooks company file on an SMB share running on the setup I am describing? Thanks