If you were thinking about getting an HD DVD or Blu-ray player, you might want to read this article at Businessweek first. Unless your TV has the right connectors, you won't be able to play movies at their full resolution.
The new content-protection scheme would be the first time any consumer electronics purchaser -- not just those who try to break copyright laws -- could be penalized. In this case, even if you have a perfectly equipped TV, content providers retain the right to automatically downgrade the picture quality because of piracy concerns. Current DVD releases like Batman Begins and Walk The Line include software to prevent unauthorized duplication, but still play normally.

New software included on both Blu-ray and HD-DVD releases, however, will automatically slash the image, making it only marginally better than current DVDs, unless consumers have a relatively new connector and cable called HDMI to hook up players to their televisions. Only one in 20 HD sets sold to early adopters over the past few years has the right version of the connector. Only 15% of new sets sold this year will include it, and deliver the full 1080 resolution capable of showing such detail.
Thankfully, Sony Pictures, 20th Century Fox, Disney, Paramount and Universal are not planning to use the new copy protection, at least on their initial releases. If you'd like to read more, the entire article can be found here.