Cause there's been nothing but trouble with the drivers in the past. Even if it have improved, they do not longer get my coins. Their special optical connections is a negative thing, and there's several cards that preform better as well. This is based on a few facts and my opinions. So don't shoot me. I'd go for a Asus Xonar card instead. Those look really good on paper. Gotten good reviews as well.
The J River HTPC's are definitely promising. Have to get some reviews of them first before I can comment.
If it was up to me, I'd do it this way (sorry, got a bit carried away with my own dreams here):
HTPC (livingroom?)
Reciever for surrond and stereo sound
HTCP, obviously (dual core or quad, 4 GB ram)
Asus Xonar Soundcard (optical output to reciever), or directly to the TV if it supports it
Radeon 5850 or 5750? (HDMI/DVI and Displayport to reciever), or directly to the TV if it supports it
Gyration as a everyday use remote control
Dinovo Mini when you have to have that Keyboard
Tremote (remote control of HTPC)
Small touch screen based laptop
HTPC (kitchen?) - Connected to Media Library
Small case (fanless built into the wall?)
Lower end CPU
Lower end GPU
Touch Screen
Server (Media, not library server)
Quad core
Huge case
Plenty storage (preferably raid)
I would buy file server and connect all the HTPC's to this one. Having all the media locally have it's downsides. Especially if you want to turn it off at times, and others want to access the media. But IF you use the HTPC as a HTPC/media server you can drop the other Server and use the Tremote function directly on the HTPC. THAT is a cool thing. Get a cheap laptop with touchscreen and flick away from your couch! You'd also get the server library functions, which improves multi client support. Let's just hope that auto sync feature get's implemented soon!
The downside of a multi-client-to-server approach is that you can't run a library server AND connect to your HTPC with the Tremote function. That's my problem today. So I'll probably end up with duplicated libraries on all clients, shared media from the server and Tremote to the HTPC.
I'm not an expert on multiple zones. But you can use up to 3 zones in stereo from one surround card and reciever. Add a reciever or a stereo and another sound card, and you have more. The sky is the limit!