Engadget put together a review of all of the currently available Netflix streaming devices, including the Xbox 360, Roku's Netflix Player, TiVo HD, and several Netflix-enables Blu-ray players. The winner?
So, who's the winner? Well, straight up we'd give it to the Samsung for picture quality alone, but really, it depends on your needs, since there isn't a bad choice in the group. If you're the sort of person with a stacked A/V rack, you'll probably find that you've got one or two Netflix-capable devices like the TiVo or Xbox 360 already -- ubiquity is the company's ultimate goal. If you're starting from scratch, we'd recommend the Samsung or LG so you can maximize your Netflix membership -- you need something to play those DVDs and Blu-ray discs you get in the mail, after all. If you've already got your physical playback situation sorted and you just want to dip a toe in the water, the Roku's a fine choice -- sure, it doesn't deliver as perfect a picture as some of the other options, but for $100 it's hard to beat.
I agree that the choice of a Netflix streaming device really depends on your situation. If you already have an Xbox 360 or TiVo HD, the choice is easy, but if you are also shopping for a Blu-ray player it gets a bit more complicated. One thing to watch out for are additional things you need to buy, such as a wireless connector (up to $100) or Xbox Live Gold membership ($30 - $50).