Someone at the AVS Forum has posted an interesting interview with Maureen Weber from Hewlett Packard, who discusses why HP moved from being a supporter of Blu-ray to a supporter of both formats. The interview was originally published in the HD DVD Newsletter though I haven't seen the original.
Weber's answer to why HP now supports both formats:
HP wants to ensure that its customers have a choice in high definition. HP is committed to providing customers with the seamless interoperability needed to store high-definition digital content easily on either a PC or a digital entertainment device. We felt that HD DVD offered several mandatory features for hardware that were important to offering a great consumer experience across the board – such as mandatory support for a network connection, for secondary encoders used for picture in picture, and for HDi to allow interactivity. Support for HDi is also incorporated into Windows Vista, which was a critical requirement of HP in our decision, given our plans for the personal computer over the next several years.
She also talks about key advantages of HD DVD over Blu-ray, and the advantages of a dual-format player.

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