I think you may be misunderstanding what an ATV does. It will stream content from your iTunes library, stream Netflix videos and YouTube. You can also rent movies and TV show directly from the iTunes Store. You can't watch broadcast television or access websites such as NHL.com. Your needs may be better served with a Mac Mini.
As far as I know, you cant use a monitor for viewing from the ATV, though I could be wrong about that.
If if misunderstood what you're interested in doing, please explain further.
Best of luck.
The ATV is intended to be connected to a TV, so, yes, you can use your TV as a monitor for an ATV. As was previously pointed out, however, the ATV is strictly a player for iTunes files, so you can't watch NHL, Hulu, or anything else that isn't in your iTunes library or available directly from the ATV menu.
The information that it does not work is true for the present System Mac OS X Lion,
but the features of the next version "Mountain Lion" are already on the website of Apple: http://www.apple.com/macosx/mountain-lion/features.html#airplay
Behind the function "Air Play Mirroring" is exactly the feature that you were asking for.
So have a bit of patience and look forward to this great new feature, as I do, because I can surf in the internet and do anything elso on my Mac with the help of the wireless keyboard and Magic Touchpad from my couch.