Well. I am thinking about a little different direction for my HTPC build.
Now I am thinking if I should go with Mini-ITX with Atom CPU or EXXX CPU
Here is what I have so far: (My biggest question is about CPU/Motherboard)
Option 1)Motherboard/CPU/Video Combo
ZOTAC IONITX-F-E Intel Atom 330 (1.6GHz, dual-core) NVIDIA ION Mini ITX Motherboard
(Have Onboard Video Chipset NVIDIA GeForce 9400 and Wifi) - So probably will play 1080p just fine and able to connect me to my net-work. http://www.newegg.com/Product/Product.aspx?Item=N82E168...
If I were to pick between your two ITX boards, I'd pick the GeForce 9300 solution with the E3300 Wolfdale CPU. Before you trip on the name 'Celeron' read the reviews. It's the perfect HTPC CPU that isn't Clarkdale.
My worry with the Atom is what if the piece of software you aren't using doesn't take advantage of GPU acceleration? It will be very slow. And, it's expensive for what you get!!
What front-end are you going to run in Linux? XBMC? I think right now, you'll have to check, but XBMC Linux does a better job with GPU acceleration in Nvidia GPUs. You might get better driver support too. Not sure.
I also heard that Nvidia is most secure in terms of drivers support and tat it will work for sure.
But the mobo which rwpritchett linked also look very nice. However I don't know how H55 work under Linux. Somewhere I was reading it works under newer kernel. But I kind of want to hear it from someone who also use it as HTPC.
That CPU looks pretty good. Maybe I will go with this.