The latest version of mplayer should be able to decode the hi-def audio codecs, but I still think you need a beefy system to play the AVC encoded stuff at a reasonable rate.

As soon as it’s possible to play HD DVD and Blu-ray discs in Linux natively with full support for menus and the like, that will be the day when I switch my media PC from Windows to a Linux based box. That is the only thing really stopping me from switching, as it takes me about 2 hours to rip a 25 GB HD DVD on this system, which is just too slow for my tastes. That, plus then I have to deal with the lack of storage issue (don’t have enough capacity to store my entire collection without re-encoding it to something smaller, which would then take up even more time).