en doom9.org, comentan que Windows Vista igual vendrá con compatibilidad para HD-DVD:

In what may just be a move to put more pressure on the Blu-Ray camp to cave in on the excessive copy protection issues, Microsoft has announced that their upcoming Windows Vista will support HD DVD, or may shortly after its release and that there are technical difficulties when it comes to Blu-Ray and Vista. But with about a year from its release, many things can still change.