Vini, There are loads of distribution boxes, I was never involved in ordering them, my job was to provide the content for the PC's. The distribution boxes could take outputs in several forms, from RF or Scart depending on what was required.
I'd definitely not recommend wireless video senders. I'd much prefer a cabled solution. With 50m i doubt there would be a problem, but you can always get booster signals (but i doubt you would need it)
http://www.maplin.co.uk/Module.aspx?...9413&doy=18m11
Somethign along these lines with a quick google, (at £30 you could try stuff out assuming you had screens to play with)
But i'd be looking to pay £100-150 for something with good quality connections rather than just standard RF to display to plasmas.
TiG