Well, I am now up and running with openelec on a 2G SD card. Two USB drives (1.5TB total) and an NFS share (750G or so). Using my Droid2 as a remote. Wired networking. 5.1 DTS is working over optical. I can't even hear the PC when it's on.
Running 3.0-Beta2. Mostly all is good. Couple of minor things, which could just be me not setting things up correctly, but the movie playing is flawless.
Way better than a WDTV.
I may have to try moving the USB drives back to the server to see if I can stream my blu-ray rips over the network. WDTV forced me to put all my blu-ray rips on locally attached drives, leaving the SD rips on the network.
I did find it odd that turning subtitles off is under the audio menu....but oh well.
Final hardware:
CPU: Intel Celeron 2.5GHz
MB: ASRock H77M
Video: Asus GT610, fanless
Case: Coolermaster
PS: Antec
RAM: 4G
-john