Building a low-power FreeBSD media server

I'm planning on building a home file server for serving media files
across my home network. I want it to be easily expandable, and am
planning on using FreeBSD and ZFS to accomplish this. This question is
really more about hardware. Because the server will be running 24/7,
and because it won't be doing anything particularly intensive, I want
it to be as low power as possible. An obvious starting point,
therefore is a VIA powered mini ITX board. Since it's just a file
server, all I should need besides that is a bunch of hard drives, and
a case to hold everything. This is what I've come up with so far, but
I'd be interested to hear if anyone has any criticisms/suggestions:

The JetWay J7F5M1G2E-VHE-LF motherboard (VIA C7) will give me a low
power processor, gigabit ethernet, two SATA ports, 1 PATA port, and a
PCI expansion slot which will allow me to add 4 more SATA ports. So
for about $350 plus the cost of a case, power supply, HDDs, and RAM, I
should be able to put together a pretty low power file server with
upwards of 6 TB of raw storage. The only real issue remaining is
finding a case that's big enough to hold 6 HDDs (maybe 7 if I decide
to use that PATA port for the system drive) and has the mountings for
a mini ITX mobo.

Does anyone see any problems or room for improvement with this plan?
.