Anybody do this?

Having owned it for several years, I recently ( ) discovered that my XBox console will double as a media extender, which means that I can stream media from the 'net to my t.v./home theater. I can't see that I'd actually ever want to do this, unless I can, with stable connectivity through my 802.11n wireless router, stream in HD and surround sound.
Can I actually achieve this? Do I need an acount with Netflix or some other "provider"? What's it all cost?

Where's Daniel? :