As previously mentioned, 1920 x 1080 , or 1080p, is full HD resolution, and is in the 16:9 aspect ratio. (16:9 is the aspect ratio of most widescreen TV's, 16:10 is the aspect ratio of most widescreen monitors.) But if a frame that large takes too long to render, the other popular widescreen size is 1280 x 720, otherwise known as 720p. This is also in the 16:9 aspect ratio, and will do for pretty much any high definition presentation, unless it is being mixed with video of higher resolution, in which case it would be good to go for 1080p.
16:9, for HD I'd suggest 1920x1080 (or is that Blu-ray)
Blu-Ray, HD-DVD, and every other medium all use the same resolutions for presenting High Definition video; the differences are the type of disc (blue or red laser) being used and the hardware being used to read and display them.