We don't stream movies through the computer, because our monitor is smaller than ideal, but we do stream music through it all the time. For movies, we stream through Netflix and run it through our Xbox 360 in the living room, and through our Roku in the bedroom.
I have been wanting to set up streaming to my TV in the bedroom. I have seen the Roku boxes in the store and wondered how well they worked. What's your opinion of Roku?