His recommendations have gotten fairly old now, as he doesn't mention the P45 nor X48 chipsets. Also he doesn't seem to know about Silverstone, Origen, or Moneual cases. So I've had to start research over from scratch. Good effort though.
So far I have it narrowed down to the Moncaso 932 case and one of these:
Mobos (P45) Mem PCIe USB Sound Power
+ P5Q3 Deluxe/WiFi-AP DDR3-dual-1600 16G 3(16),2(1),2(PCI) 10 ADI® AD2000B 8 Ch HiDef 16ph
P5Q-E DDR2-dual-1200 16G 3(16),2(1),2(PCI) 12 ADI® AD2000B 8 Ch HiDef 8ph
+ P5Q Premium DDR2-dual-1200 16G 4(16),1(1),2(PCI) 14 ADI® AD2000B 8 Ch HiDef 16ph
Maximus II Formula DDR2-dual-1200 16G 2(16),3(1),2(PCI) 12 SupremeFX X-Fi 8-Ch
P45 Diamond DDR3-dual-2000 8G 2(16),2(1),2(PCI) 12 X-fi Xtreme 268/388w
- X48 Platinum 4(16),2(1),1(PCI) 12 260/357w
No clear winners here. I want integrated graphics (for the case LCD) and lots of room for PCI cards (whether PCIe or otherwise). I don't know which PCI, cards are coming in these days, so it's a question whether more 16bit or 1bit is better.
I really like the idea of ASUS' EPU-6 Engine, assuming that it's not just marketing hype, much less whether it works in Linux.
Of course for PSU it will be a Silver or Gold-rated one on the 80Plus site.
... Will be running MythTV over Kubongo, and HD DVR will be this machine's main role. The PCIe video card will drive my projector, and must have BluRay hardware decode; haven't gotten that far yet tho. I hear R5000 HD support for MythTV is unreliable, but HD-PVR has lots o' problems too. What's a poor girl to do?