I haven't made the move to a high definition DVD player yet, because frankly it reminds me of VHS or BETA debacle. Who will win? (Blu-Ray is in the lead)
The decision isn't ours because the availability of content will depend on what the studio magnates decide to put their movies on. More studios, including Sony and Disney, support Blu-ray exclusively. Only Universal Pictures supports HD DVD exclusively. Warner Bros. and Paramount release films in both formats.
Here is a High-Def Video Superguide, thanks to PC World.
UPDATE: Paramount dumps Blu-ray which means Blu-ray loses access to Dreamworks Pictures, Paramount Vantage, Nickelodeon Movies, MTV Films, and also – notably – Dreamworks Animation.