I opted for the Roku. Got the XD version just a couple of weeks ago. This one is HD via HDMI. The player overall, have to give it 4 stars for what it does. It does have a ton of channels you're not going to get on the ATV. Went with this one just to experiment as I got it for <$60.

With the Roku, only the top end version of the player has the USB port which is "suppose" to support streaming from an external drive. Although, they keep pushing back the firmware to do this - now slated for January. Looks like we're waiting to see whether the ATV gets hulu first or the Roku gets the ability to play your existing content first.

It will only support .mp4 and .m4v with h.264 - same as iTunes (iTunes also supports .mov). Only with the Roku, your drive will have to be directly connected to the unit. It does not support streaming the content that sits on your computer or anywhere else on the network. This means moving the drive around - to the computer when you want to add more content and back to the Roku when you want to watch the content on your TV. That's gonna be a pitr compared to just turning on the device and playing your media from wherever it sits on your network as the ATV will.

And I hope all your content sits on a single drive with the Roku. Oh the pain it's going to be if you have multiple drives, and now you'll have to figure out which drive that movie sits on before you move it to the Roku instead of just streaming it. Have fun with that.

I also purchase a fair amount of content from both Amazon VOD and iTunes. Have to say doug you are way off base thinking Amazon has some big advantage over iTunes.

Amazon - can be used on up to two (2) computers
iTunes - can be used on up to five (5) computers

Amazon - your hard drive dies on one of the computers that is authorized - guess what - you're down to one - there is no way to go unauthorize an existing machine without opening up the Amazon app on the machine that was authorized - I already have this situation - haven't a clue what happens when the next hard drive dies - guess I just lose all access to my content via a computer from then on.

Amazon - can put that content onto your iPod/iPhone/iPad - not happening
iTunes - all your purchased content can be put onto these devices

rental vs buying between the two of them - there really is very little difference here - for purchasing, you'll find only random differences between them. For the most part you find the same stuff at the same price - Amazon is typically $1 cheaper on their TV season pricing - at least on the ones I have actually bought.

Amazon has stuff iTunes doesn't have. iTunes has stuff Amazon doesn't have. Amazon has stuff in HD only available in SD on iTunes. iTunes has stuff in HD only available in SD on Amazon. iTunes has stuff for rent not available at all or only for purchase on Amazon and typically they are for sale at the same price as Amazon.

imho - anyone only using one of these two services without comparison shopping on the specific shows you want, is making a big mistake

This is sort of like the Win vs OS X fanboy stuff. They each have their place and I use both Windows and OS X. I also use iTunes and Amazon VOD. I get the best of both worlds without limiting myself.

Oh and btw: For those that haven't seen The Walking Dead - Amazon has the season (only 6 shows) for sale at $4.99 right now in SD - worth the price if you're at all into zombie shows. In HD, it's $2 cheaper than iTunes - So, will you ever want to put it on one of your iDevices or not is the question for that $2 extra.