This thread coming back up is good timing. I ended up not getting a Roku, because really what I want is something to allow me to watch any old video on the internet on my TV. I already have other ways of watching Netflix on the TV and have no desire for a Hulu membership. So no Roku. But at my old place my TV was very close to my desktop, so I used the DVI to HDMI cable to watch things on the TV. It worked out well, but I moved shortly after and now my furniture configuration doesn't allow for that.
I just heard about and purchased a Chromecast
from Google. The reviews of the internet video streaming capabilities are mixed, but at $35 its worth a shot. It's also pretty new, and services and enhancements are sure to be coming along shortly. You plug it into the back of your TV and use apps on your smartphone or Chrome on your computer's browser to control what video plays on the TV. It's on backorder so I have had to wait 4 weeks for it to ship!