I remember reading in the past on these forums that the whole voice command thing is unreliable due to background noise, and only really works with a headset. I don't have any experience of this personally though.
Regarding hardware, Andrew Herron from Convergent Home Technlogies recently posted about their success with getting HDTV working with their nvidia cards, through myth, utilising VDPAU. I've just purchased an Asus nVidia Ion 330 board for my lounge media director, and so far I have been really impressed with it (going to play with VDPAU tonight, as my third-time-lucky RAM kit should be arriving today, having had 2 bad kits).