Link to buy:

http://www.apple.com/appletv/specs.html

Video
Video formats supported: H.264 and protected H.264 (from iTunes Store): 640 by 480, 30 fps, LC version of Baseline Profile; 320 by 240, 30 fps, Baseline profile up to Level 1.3; 1280 by 720, 24 fps, Progressive Main Profile. MPEG-4: 640 by 480, 30 fps, Simple Profile

Not quite there without Xvid / Divx and also missing VC-1. Won't be playing Blue Ray or HD DVD from your PC.

This Saphire card has a HDMI and SPDIF. The SPDIF is for input from a motherboard SPDIF out to router through the HDMI cable. If you can get the multichannel sound ffrom the MSI HDMI connector that would be even better.
http://www.newegg.com/Product/Product.asp?Item=N82E16814102032

What about HDCP compliance? Wouldn't want this monitor if it won't work with HD DVD.

There is a long list of Networked DVD players that already play HD transport streams over ethernet or from the DVD tray. The ones I know about all use the Sigma Designs EM8620L digital media processing chip. I personally use the Snazio Net Cinema HD DVD. I record HD programs on my PC and stream to the player. I also can burn the transport stream file to a DVD and play back on the player from the tray. These units playback WMV HD, Divx HD, Xvid, Mpeg1 & 2 but not H264.