To those who say Blu-ray looks/sounds better, this is 99% of the time just crap. Blu-ray and HD DVD support the exact same video codecs, and almost the same audio codecs (some differences there I suppose). On most dual-format releases they use the exact same encodes of the movies, so they look... exactly the same. Now, if one includes a higher bitrate audio track than the other, they could sound different, but that's up to the people authoring them. TrueHD and DTS-HD (two lossless surround audio codecs) are the same, for instance, because they're lossless.
Anyway, I will be supporting both. HD DVD has some exclusives, and I already have the player for my Xbox 360. I'll start buying Blu-ray discs when I have a PS3.