UTP or Coax for Video Distribution

I am setting up a Corporate TV information System. I want to run cable from Digital Media Engine (server) to Video Distribution Amplifier and out to 5 HDTV or Plasma displays. Total distance within 100 meters (300 ft). Should I use UTP cat 5 or Coax ? Wondering about signal loss and picture quality. Running both powerpoint and video files thru presentation software.