And nobody knows yet which format is likely to prevail and become widespread.
Blu-ray discs store as much as 50 gigabytes, while HD-DVD discs store as much as 30. In the future, the Blu-ray number might grow to 200, while the HD-DVD number could possibly cap at 45 gigabytes. DVDs typically store 4.7 gigabytes or 8.5 gigabytes.
The HD-DVD players are more closely tied to the original DVD technology. You can take a new hybrid disc (HD-DVD on one side, DVD on the other) and play it in an old DVD player. You can't do that with Blu-ray. But you can put the older DVDs into a Blu-ray machine. Hence, if you have a library of older DVDs, you can keep them and play them with the new players on either side.
Do you want HD movies? On bigger sets, yes. On smaller screens, I think regular DVDs look pretty good. I watched HD-DVD movies on a Toshiba Qosmio G-35 AV650 ($2,499) with a 17-inch screen. I also looked at Blu-ray on an upcoming Dell laptop. With the small screen sizes, the picture looks nice but not good enough to be a big deal. The real reason to get a writeable next-generation HD player on a laptop is for easy archiving of your hard-drive data.
The larger the screen, the more you will appreciate movies in the 1080p format. But it's worth noting that many TVs on the market at reasonable prices display movies only in 720p resolution, which isn't as good.
Also, the anti-piracy provisions are worth paying attention to. If you're interested in that, do an Internet search on HDCP, or high-bandwidth digital copy protection, to get an explanation of why this prevents you from playing unauthorized discs, among other things.
For now, there are more than 100 movie discs out for each format. In the long run, HD-DVD faces big problems. It stores less data, and only three of eight major studios have agreed to release movies on it. Blu-ray stores more data, and seven of eight studios support it.
Blu-ray discs cannot play on older DVD players.