I use My X-Box 360's drive (hitachi drive I believe) It reads any DVD and makes non-HD DVD's look like HD.
-And as for original X-Box games, The system automatically upscales it from 480p to 729p without changing anything on the disc.
I'm also using the 360's new NXE (let Sony try that!

)
It's best to get Widescreen DVDs or ones that have that option in their menu.
Most modern DVD players have aspect ratios (and some resolution)
I use 1080i and it looks great until I watch non-HD TV channels, so I usually stay with Discovery Networks HD (yes I love Discovery Channel, Science Channel, ETC.)
Sony's Blu-Ray is horrible, it uses the same technology as a Playstation One & Playstation 3. It reads blue colored discs using a blue ray.
-It's like trying to get traction in the snow by using white tires!