Alri,
You will have problems sending dvd over coax, as copyright protection on some dvd's cause problems and distort the pictre (I've been down this road).
You want a solution like KAT-5 which I think is one of the more affordable systems, but there are others. As always, my favourite reference point for this kind of stuff is
www.letsautomate.com, specifically tv distribution system KAT5 here [broken link removed]? . The thing you will need to c onsider is that you also distribute IR, which KAT5 does and will therefore allow you control your sources etc, and is also a big advantage for automation too.
There are other products about, have a more in depth look at the letsautomate site. Also is an excellent reference point for all things HA.
One of the other things you wight want to consider is windows media centre. Use a media centre pc to store all your dvd's etc, (or even a big NAS which you would use along with your Sonos) connected to a media centre pc, and then use media centre extenders to distribute to each room. Definately worth a bit of research on this one I think.
Sonos is excellent, I highly recommend it, but having seen that you also want to distribute video, the only thing I would say is that a combined audio and video system might be worth looking at ddepending on your buidget etc.
But I still stick by my Sonos, if you do get one, you will not regret it.
Regards,
Eamon