High Def DVD FAQ

About.com has a nice beginners guide to the next generation DVD formats. The key point to remember that can be taken from this article is that both Blu-ray and HD DVD players will be compatible with the current DVD format. In fact, most players will upscale to the same resolution as Blue-ray or HD DVD. This won't give current DVDs the same picture quality as a high def DVD but it will be an improvement.

From the article: 

There are films and video content now available on both the Blu-ray and
HD-DVD format. By the end of 2006, expect to see several hundred titles
available. Prices for the titles are about $5-or-$10 more than current DVDs.
Prices for movies, just as for players, are expected to go down over time as
competition heats up and more disc quantities of each film are produced.