Arcsoft TotalMediaTheatre 3 is extremely good and still supports HDDVD. It also integrates with MediaCentre rather than launching as a console like powerDVD.
Not sure when bitstreaming for the HD5xxx card will come from them, however the Asus Xonar HDAV 1.3 still outputs HD Bitstream with TMT3.
@OP.... I couldn't agree more, albian has almost cracked PAP protection for use within MPC-HC and FFDShow tryouts Audio decoder. I'll be trying this tonight when I get home