Save that $99 for an Apple TV.
If you just want to watch movies rented from Netfllx on your TV all you need is the latest Netflix iPhone app, iPhone AV cable and an iPhone 4. You can save the money for an Roku or new Apple TV. The only down-side is that the iPhone 4 video out via AV cable is only supporting SD resolution. If you have an HDTV you are still better off getting a Roku box for Netflix streaming.