HDTV is the TV. If you want the best quality, then you need to buy a FULL HD TV, the HD Ready ones you see cheap in argos, currys etc, are usually 720p where as the full HDTVs are 1080p. The number refers to the amount of lines that make up the screen, the more there are the higher the definition.
HD-DVD is losing the format war, so I'd go and buy a Blu-Ray player if I was you. Blu-Ray has won basically because it can fit more info onto one disc, and has the future capability of having FOUR layers on the disc. Mental!
If you want a real bargain, got and buy a PS3, they play Blu-Ray, are full 1080p Compliant (with the right TV) and works out better value for money than a standard Blu-Ray player!