Simplest home streaming solution

Hello there my fellow vergins!

Let's say I have a 42 inch TV. I also have a Windows Vista PC, full of video files. Some are .mkv, some are avi's, god knows what codecs. All I know is that they always played well with MPC-HC combined with the CCCP pack. But my pc sits in a room, my TV in another. I do not want to run an ethernet cable between them. I currently have a 802.11 G router, but would consider upgrading to an N one to ensure smooth playback.

My questions are:

What is the simplest way to stream 720p content to that TV? Boxee, Revue, Roku, something else? I don't care for other online services, I just want to stream the movies the simplest way possible.

Is a dual band router recommended, necessary, obligatory?