My house living room go fully High-Definition earlier this year (well visually at least), HDTV and a Blu-ray player complete the set-up.
I use my PlayStation 3 as a Blu-ray player, since everyone on the internet said that PlayStation is the best Blu-ray player out there. Then we bought a LED High-Definition television, capable of outputting crystal clear 1080P full HD image.
If few of you don't HD means (living in the cave maybe?), HD means your image is displayed at horizontally 1080 pixels, a hell lot more than than SD, which just displayed at 480 pixels horizontally.
I don't know the full capabilities of Blu-ray before the house new TV was purchased. When I first put Transformers disc into my PS3, I was blown away. It just left DVD in the dust, although Blu-ray loading times are much slower. But when you have time for a 2 hour movie, you just don't care.
Optimus Prime never look this
A short description of what I saw when I watched Transformers BD:
Everything, dents on Bumblebee's Car, scratches on Megatron's body, Optimus Prime's teeth, sweat and blood on soldiers faces, are displayed in crystal clear, meticulous detail. You will never see anything close to this quality.