You can see the improvement in picture quality with a good power conditioner.
Does power conditioning really matter?
I have a friend who is setting up a budget system with a nice hi def plasma (Pioneer PDP-5020FD) and an entry level receiver (either Denon AVR 1909 or Onkyo TX-SR606) who is wondering whether the Monster conditioner for $300 that the salesperson is pushing is really necessary over a plain surge suppressor. Will this make a difference in his system?