So I am looking to build a NAS with
1. DLNA/UPnP AV server
2. Raid 0/1 JBOD support
3. Decent network thruput.
4. Low power use.

I'm thinking Intel Atom with nVidia Ion platform

This is to replace a D-Link DNS-321. After four days of working on it, I'm throwing in the towel.

On paper it looked great. Cheap NAS. Web interface control. Holds two SATA drives with Raid 0, 1, JBOD. Low power consumption. UPnP AV Server (DLNA)

1. Extremely slow transfer rates. ~2.5MB/sec over gigabit network
2. DLNA (AV Server standard) is broken.
3. Doesn't work with 4K sector hard drives.

So I went online to new-egg and started shopping for alternatives. Seems there are a lot of these same devices made by different manufacturers with subtle variations in design. I suspect they are made by some OEM tiawan mfg. And they all suffer from the same design flaw with little to no support.

I went with an under-volted Athlon X2 5200, clocked down to 2GHz, on a 740G motherboard running Linux Mint.
Mediatomb for the media server (about the only thing it can't serve to is an XBox360) and also running MythTV to record DVB-T.

It idles relatively high (40 watts), but I prefer having the additional computing power available so I know I can throw more things at it in the future if need be. For me, ION-based machines have always seemed to be video-centric with a lack of CPU power creating an unbalanced system.

Do you have a PS3 by any chance? Wondering if Mediatomb > PS3MediaServer.
I don't see the point of Ion either.

OP: If you aren't going to go with the suggestion above which is a good one, get a D510 if you are not transcoding or an i3 530 if you are transcoding.

Yup, I've set Mediatomb to transcode DIVX files on the fly and they play back just fine on the PS3, it even allows the 1 minute preview jumps. I think there's 2 lines in the config file that need to be changed (it even has remarks beside them so you know which two) and it's up and running very quickly.
A bit more editing of the config file and I can also stream to my Samsung TV which, although not as comprehensive as the PS3 (you can play or pause DIVX files), it's a lot quicker to start.

Look into a QNAP TS-119 + 2.5" Fujitsu 500GB drive(s). Uses around 7 watts during load and supposedly does 50-75Mbps over gigabit lan (I'm on 100Mbps, so I can't verify that claim). The main downside would be real-time video transcoding, which would very likely be too much for the 1.2GHz ARM CPU.

Note that the DNS-321 uses a 400MHz ARM CPU while the TS-119 uses a 1200MHz CPU, so it's pretty safe to say the network speeds will be much higher.

First off, about " raid 0, 1, JBOD" forget that man, those standard are for chumps. You want RAID5 baby.

1. It allows you to recover from a hard drive failure and use more of your data. All, it will cost you in the loss of 1 drive in your array.

Example, if a 4 drive array, you will have 3 drive's worth of space available. ( 75%)

In a 8 drive array, you will have 7 drive worth of space available. 87.5% available.

In Raid 0, you lose 1 drive and you lose all your data on all drives, RAID 1, you will only be able to use 50% of your data. JBOD is not even raid, its just allows you to display your drives are 1 drive but they remain separate. This would probably be your second best option but kind of a waste for a raid system not to do raid and give you projection against a hard drive breakdown.

I would get a popcorn hour which comes with its own media streaming software. Just use a PC to reference the network drive of your NAS system( or run the software on your NAS as long as it has windows)

What is what I do in my theater setup.