dvd distribution is tricky. If you modulate it onto coax, which is the cheapest way, its distorted by copyright protection (to prevent you from recording onto a video).
DVD will and can be distributed over cat5, but as previous poster mentioned it is expensive. Near future (or even now) media distribution around your house will be via CAT5 and media centre extender type devices streaming from a networked dvd player or hard disk.
I would plan to have cat5 presented near and TV point and brought back to where your main audio/video room is going to be. In reality, I would plan to have one room equipped with high quality audio/video, which is where you will be watching most of your home entertainment.
Other rooms with t's are more than likely going to be portable tv's etc, and satelite etc can be distributed via coax to these type of screens in the short term (but do provide a cat5 point next to tv for future devices as I mentioned).
You can buy a dvd player for 30 quid now, which is a hell of a lot easier and cheaper that distributing dvd from one source all around the house. I think we are near the point where this type of thing will be feasible and affordable, but not there yet.
Wexfordman