What was the bit rate of the samples that you tried?
A HD-DVD will usually run around 20mps for VC-1 and 30mps for MPEG-2.
Plus the decoding of such a large bit stream will greatly increase your processing needs.
I seriously doubt that
the best minimum setup would be a A64 3500+ and a Radeon X1600 Pro.
will be enough for 1080p smooth playback.
Also, if you plan of using HDMI with TrueHD, this is another high bandwidth decode that must be done.
I hope the new players of PowerDVD, WinDVD, ZoomPlayer and TheatreTek will use multi-threads to process the video/audio streams efficiently.
My Prediction of a min system will be
CPU --- AMD 4000+ or Intel E6400 (both D dual core and not OC'ed)
Memory - 1G min/ 2G with Vista
Video - Nvidia 7950GT or ATI X1950Pro (Reason is enough GPU prower, HDCP compatiablity, and sound integerated HDMI)
That's what i will shoot for next year.