There are a few manufacturers who make DVD players that support both formats (HD-DVD and Blu-Ray). That’s the way to go for now - at least until one of the two formats wins. No one wants to buy into another 8-Track or Betamax fiasco.
You could be an HD-DVD player and a blue-ray player for the cost of a player that supports both formats by shopping around...
Don't forget the Laser Disk. Unfortunately, I fell for that one and I still have heart burn over it.